# Bob

Popular questions and responses by Bob
1. ## Economics

A monopoly firm faces a demand curve given by the following equation: P = $500 − 10Q, where Q equals quantity sold per day. Its marginal cost curve is MC =$100 per day. Assume that the firm faces no fixed cost. You may wish to arrive at the answers

asked on May 3, 2016
2. ## Chemistry

Assuming that sea water is a 3.5 wt % solution of NaCl in water, calculate its osmotic pressure at 20°C. The density of a 3.5% NaCl solution at 20°C is 1.023 g/mL.

asked on April 13, 2010
3. ## Pre Calculus

Find all $2 \times 2$ matrices $\bold{A}$ that have the property that for any $2 \times 2$ matrix $\bold{B}$, $\bold{A} \bold{B} = \bold{B} \bold{A}.$

asked on September 20, 2017
4. ## math

I look at a random time of day at a digital clock (that shows times from 1:00 through 12:59). What is the probability that (ignoring the colon) I see a palindrome such as 8:08? Express your answer as a common fraction.

asked on November 15, 2012
5. ## Chemistry

Balance the following equation for a half reaction that occurs in basic solution. Use e– as the symbol for an electron. SO3^2- ---> S2O4^2-

asked on May 4, 2014
6. ## LCM of two numbers?

lcm of two numbers pi/3 pi/2 How do I do it? Would it be pi or pi/6? Thanks

asked on December 15, 2013
7. ## Microecon help

Please help! Review for a test and am so lost! (1) An article in the New York Times (Oct. 18, 1990) described a successful marketing campaign by the French champagne industry. The article also noted that “many executives felt giddy about the

asked on September 3, 2007
8. ## Chemistry

The equilibrium constant, Kp, equals 3.40 for the isomerization reaction: cis-2-butene trans-2-butene. If a flask initially contains 0.250 atm of cis-2-butene and 0.145 atm of trans-2-butene, what is the equilibrium pressure of each gas?

asked on December 2, 2014
9. ## Chemistry

Kc is 1.67 × 1020 at 25°C for the formation of iron(III) oxalate complex ion: Fe3+(aq) + 3 C2O42-(aq) [Fe(C2O4)3]3-(aq). If 0.0200 M Fe3+ is initially mixed with 1.00 M oxalate ion, what is the concentration of Fe3+ ion at equilibrium?

asked on December 2, 2014
10. ## Chemistry

Which of the following ionic compounds has the highest melting point? Help: Lattice energy Select one: a. Cs2O b. K2O c. BeO d. SrO e. LiF f. CsI

asked on November 10, 2014
11. ## Chemistry

In a particular redox reaction, MnO2 is oxidized to MnO4– and Cu2 is reduced to Cu . Complete and balance the equation for this reaction in acidic solution. Phases are optional. MnO2 + Cu^2+ ---> MnO4^- + Cu^+

asked on May 4, 2014

Claire has borrowed $\$5,\!000$. She plans to pay off the loan in full after two payments. She will make one payment in 3 years, then another payment in 6 years. The second payment will be exactly double the amount of the first payment. How much is the asked on April 4, 2017 13. ## Math Of 30 students, 12 play football, 17 play soccer, and 5 play both, how many play neither? asked on March 12, 2013 14. ## Statistics 50 employees in an office wear eyeglasses. 43 have single-vision correction, and 7 wear bifocals. If two employees are selected at random from this group, what is the probability that both of them wear bifocals? What is the probability that both have asked on October 2, 2019 15. ## Physics A 1200-kg frictionless roller coaster starts from rest at a height of 24 m. What is its kinetic energy when it goes over a spot that is 12 m high? asked on May 10, 2012 16. ## math Three water pipes are used to fill a swimming pool. The 1st pipe alone takes 8 hours to fill the pool, the 2nd pipe alone takes 12 hours to fill the pool, and the 3rd pipe takes 24 hours to fill the pool. If all 3 pipes are opened at the same time, how asked on May 26, 2011 17. ## algebra 2 During the first part of a trip a canoeist travels 26 miles at a certain speed. The canoeist travels 8 miles on the second part of the trip at a speed 5 mph slower. Total time is 3 hours. What was the seed on each part of the trip asked on April 21, 2013 18. ## geometry The two non-parallel sides of an isosceles trapezoid are each 7 feet long. The longer of the two bases measures 22 feet long. The sum of the base angles is 140°. a. Find the length of the diagonal. b. Find the length of the shorter base. Round your asked on July 26, 2017 19. ## statistics A university dean wishes to estimate the average number of hours his part-time instructors teach per week. The standard deviation is 2.6 hours. How large a sample must be selected if he wants to be 95% confident of finding whether the true mean differs asked on March 30, 2011 20. ## math Between which two consecutive integers does the radical square root of 15 lie? asked on September 4, 2019 21. ## Physics The density of copper is 8.96 g cm^−3 and its molar mass is 64 g mol^−1. Calculate the mass of 1 atom of copper. asked on July 11, 2020 22. ## Math Katie makes 65% of her shots from the free throw line. Can you determine how many consecutive free throws she must make in order to increase her percentage to 68%? Explain. asked on July 2, 2016 23. ## math Anne wants to tie a support line from the top of a 50 foot radio tower to an anchor spot 30 feet from the tower’s base. Approximately how long will the line need to be? asked on June 20, 2013 24. ## physics a small bead can slide without friction on a circular hoop that is in a vertical plane and has a radius of 0.100 m. The hoop rotates at a constant rate of 3.00 rev/s about a vertical diameter. Find the angle beta at which the bead is in vertical asked on October 24, 2011 25. ## chemistry The reaction: A + 3 B = D + F was studied and the following mechanism was finally determined A + B = C (fast) C + B = D + E (slow) E + B = F (very fast) The step with largest activation energy is a. the first step b. the second step c. the third step d. asked on February 24, 2012 26. ## Math, Please Help!!! a hot air balloon is rising vertically 10 ft/sec while the wind is blowing horizontally 5ft/sec. Find the speed of the balloon and the angle x that it makes with the horizontal. I know that the speed of the balloon is the square root of (10)^2 + (5)^2, but asked on November 10, 2011 27. ## science Two stones are launched from the top of a tall building. One stone is thrown in a direction 30.0degree above the horizontal with a speed of 10.0m/s ; the other is thrown in a direction 30.0degree below the horizontal with the same speed. Which stone lands asked on September 8, 2008 28. ## geometry the surface areas of two similar solids are 340 yd2 and 1158 yd2 the volume of the larger solids is 1712 yd3 what is the volume of the smaller solid? asked on May 30, 2013 29. ## Math A biologist has determined that a particular osprey has a 70% chance of catching a fish on any given day. Carry out a simulation of 20 trials using the random number table below to find the probability that the osprey will actually catch a fish on all of asked on May 20, 2014 30. ## chemistry Which of the following is not amphiprotic? a)H2O c)NH4+ e)all choices are amphiprotic b)HSO4 – d)H2PO4– need help! asked on March 17, 2012 31. ## math The table shows the number of people that went to see a movie last week. Use these statements to complete the table. On Thursday, 60% of the moviegoers were male. On Friday, 35% of the moviegoers were male. On Saturday, 70% of the moviegoers were female. asked on January 26, 2017 32. ## Chemistry a) Which of the following reagents would oxidize Zn to Zn2 , but not Ag to Ag ? Answers are: Co2+ Ca2+ Br2- Br2 Co or Ca b) Which of the following reagents would oxidize Ag to Ag , but not Cl– to Cl2? Answers are: Co Br- Br2 Co2+ Ca2+ or Ca asked on June 2, 2014 33. ## Chemistry Calculate the total quantity of heat required to convert 25.0 g of liquid CCl4(l) from 25.0°C to gaseous CCl4 at 76.8°C (the normal boiling point for CCl4)? The specific heat of CCl4(l) is its heat of fusion is and its heat of vaporization is asked on April 13, 2010 34. ## Math Peter bought 24 tickets for 490. Adult tickets =25 and student tickets = 15. How many of each type did he buy? asked on July 27, 2020 35. ## math two girls caught 25 frogs. Lisa caught four times as many as Jen did. how many frogs did Jen catch asked on February 3, 2011 36. ## chemistry Phosphoric acid is a triprotic acid, so H3PO4, H2PO4 -, and HPO4 2- are all acids. Which of the solutions below would have the lowest pH? 0.1 M NaH2PO4 0.1 M Na2HPO4 0.1 M Na3PO4 asked on March 10, 2014 37. ## Physics A woman on a bridge 75.0m high sees a raft floating at a constant speed on the river below. She drops a stone from rest in an attempt to hit the raft. The stone is released when the raft has 7.00m more to travel before passing under the bridge. The stone asked on November 19, 2013 38. ## physics two objects are thrown from the top edge of a cliff with a speed of 10 m/s. one object is thrown straight down and the other straight up. if the first object hits the ground in 4.0 second, the second hits the ground in ________ seconds after the first asked on August 9, 2012 39. ## physics Net force F causes mass m1 to accelerate at rate a. A net force of 3F causes mass m2 to accelerate at rate 2a. What is the ratio of mass m1 to mass m2? asked on November 5, 2013 40. ## Chemistry How do you calculate ΔSfus and ΔSvap for HCl given melting point,ΔHfus, boiling point, and ΔHvap also how do you determine the entropy change when 5.20 mol of HCl(l) freezes at atmospheric pressure. asked on April 25, 2014 41. ## Math The entrance hall to the Louvre Museum in Paris is a glass and metal pyramid with a surface area of approximately 1980 square on each side . The base of the pyramid is a square that is 35.4 meters on each side. What is the slant height of the pyramid ? asked on April 2, 2014 42. ## main ideas Scientists generally agree that Earth is getting warmer due to what's called the greenhouse effect. A greenhouse used for plants stays warm because sunlight and heat coming through the glass roof are mostly trapped. The heat doesn't radiate back into the asked on September 6, 2013 43. ## Algebra Participants in a study of a new medication received either medication A or a placebo. Find P(placebo and improvement). You may find it helpful to make a tree diagram of the problem on a separate piece of paper. Of all those who participated in the study, asked on May 21, 2014 44. ## geometry What is the most precise name for quadrilateral ABCD with vertices A(–3, 2), B(–1, 4), C(4, 4), and D(2, 2)? 1. parallelogram 2. rhombus 3. quadrilateral 4. rectangle asked on January 11, 2013 45. ## Calculus for the function F(t)=ln(t^2), let f(t)=F'(t). Write the integral from a to b of f(t) dt and evaluate it with the fundamental theorem of calculus. the integral from 1 to 3 ___ dt= __ asked on November 30, 2011 46. ## Chemistry 40.0 ml of an acetic acid of unknown concentration is titrated with 0.100 M NaOH. After 20.0 mL of the base solution has been added, the pH in the titration flask is 5.10. What was the concentration of the original acetic acid solution? (Ka(CH3COOH) = 1.8 asked on April 10, 2011 47. ## calculus A square-based, box-shaped shipping crate is designed to have a volume of 16ft^3. The material used to make the base costs twice as much (per ft^2) as the material in the sides, and the material used to make the top costs half as much (per ft^2) as the asked on November 4, 2010 48. ## Chemistry An iron ore sample was dissolved in hydrochloric acid and the iron was obtained as Fe2+(aq). The iron solution was titrated with 38.54 mL of 0.471 M Ce4+ solution according to the balanced chemical equation below. Ce4+(aq) + Fe2+(aq) -> Ce3+(aq) + asked on March 11, 2009 49. ## Chemistry What is the net ionic equation when H2SO4 is neutralized by NaOH in aqueous solution? Write the molecular equation. H2SO4 + 2NaOH ==> Na2SO4 + 2H2O Convert to ions. 2H^+ + SO4^= + 2Na^+ + 2 OH^- ==> 2Na^+ + SO4^= + 2H2O Now cancel those ions that appear on asked on February 17, 2007 50. ## Math Terry bought some gum and some candy. The number of packs of chewing gum was one more than the number of mints. The number of mints was three times the number of chocolate bars. If gum cost 6 cents a pack, mints cost 3 cents each, and chocolate bars cost asked on June 6, 2020 51. ## physics A force acts on a 2kg mass and gives it an acceleration of 3 m/s^2. what acceleration is produced by the same force when acting on a mass of (1) 1kg? (2) 4kg? (3) how large is the force? asked on October 25, 2018 52. ## Calculus Graph the function f(x)=x+4/x Graph the secant line that passes through the points (1,5) and (8,8.5) on the same set of axes Find the number c that satisfies the conclusion of the Mean Value Theorem for f on [1,8] c= Notice that if you graph the tangent asked on February 8, 2015 53. ## Math You invested$14,000 in two accounts paying 5% and 9% annual interest, respectively. If the total interest earned for the year was $820, how much was invested at each rate? asked on September 4, 2012 54. ## Physics Work of 730 J is done by stirring an insulated beaker containing 80 g of water. What is the change in the temperature of the water? Please show calculation asked on October 19, 2011 55. ## physics In the vertical jump, an Kobe Bryant starts from a crouch and jumps upward to reach as high as possible. Even the best athletes spend little more than 1.00 s in the air (their "hang time"). Treat Kobe as a particle and let ymax be his maximum height above asked on October 21, 2010 56. ## Auditing 1. Which of the following matters would an auditor most likely consider to be a significant deficiency to be communicated to the audit committee? A. Management's failure to renegotiate unfavorable long-term purchase commitments. B. Recurring operating asked on March 11, 2010 57. ## Operations Management The maintenance department of a hospital uses 816 cases of liquid cleanser annually. Ordering costs are$12, carrying costs are $4 per case a year, and the new price schedule indicates that orders of less than 50 cases will cost$20 per case, 50 to 79

asked on March 7, 2009
58. ## Chemistry

A chemist performs a series of reactions that produce binary lithium compounds. The elements include sulfur, chlorine, nitrogen, fluorine, selenium, oxygen, and iodine. The models below represent the ionic radii of compounds formed by reacting lithium with

asked on April 13, 2020
59. ## physics

(fill in the blanks) The mass of a 300 g object is _______(a). Its weight on Earth is _______(b). An object that weighs 20N on earth has a mass on the moon equal to ________(c)

asked on October 25, 2018
60. ## geometry

George plans to cover his circular pool for the upcoming winter season. The pool has a diameter of 20 feet and extends 12 inches beyond the edge of the pool. A rope runs along the edge of the cover to secure it in place. a. What is the area of the pool

asked on July 26, 2017
61. ## math

In a geometric series, t1=12 and s3=372.what is the greatest possible value for t5?

asked on June 3, 2013
62. ## chemistry

Calculate the number of carbon atoms in 0.75 L of acetone (CH3COCH3). (density = 1.3 g/mL and boiling point = 48.5 degrees Celsius)

asked on October 31, 2010
63. ## chemistry

consider a crystallization of sulfanilamide in which 10 mL of hot 95% ethyl alcohol is added to 0.10 g of impure sulfanimide. after the solid has dissolved, the solution is cooled to room temp. and then placed into an ice-water bath. no crystals for, even

asked on October 7, 2008
64. ## Trigonometry

The wheels of a scooter have a diameter of 4.5 inches. If the person riding the scooter is traveling down hill at 15.0 mph. what is the approximate angular speed of the wheels in radians per second

asked on September 25, 2014
65. ## Geometry :)

Use coordinate geometry to prove that the quadrilateral formed by connecting the midpoints of a kite is a rectangle. I have no Idea how to do this problem, so if anyone could help I would be very greatfull. :)

asked on January 15, 2013
66. ## Physics

A rock climber of mass 55 kg is hanging suspended from a rope tied to another climber of mass 65 kg on a horizontal cliff ledge. If the coefficient of kinetic friction between the climber on the ledge and the ledge is 0.45, what is the net acceleration of

asked on July 15, 2012
67. ## Economics

Suppose that some firms in a competitive industry are earning zero economic profits, while others are experiencing losses. All else equal, in the long run, we would expect the number of firms in the industry to A. increase. B. decrease. C. remain the same.

asked on November 29, 2011
68. ## Chemistry

Use the dilution relationship (Mi x Vi = Mf x Vf) to calculate the volume of 0.500 M NaOH needed to prepare 500 mL of .250 M NaOH. This is my work ? L Solution = 500mL x (1L/1000mL) = .500L ? mol NaOH = .500 L Solution x (0.250 M NaOH/1 L Solution) = .125

asked on February 28, 2009
69. ## math

What set of reflections and rotations would carry rectangle ABCD onto itself? Rectangle formed by ordered pairs A at negative 4, 1, B at negative 4, 2, C at negative 1, 2, D at negative 1, 1.

asked on September 17, 2018
70. ## Data

Bridget works part time in a shoe store. Sometimes when it is not busy, she rearranges the shoes for fun. If she takes six different pairs of shoes and rearranges them in a row, in how many ways can she rearrange them so that no two shoes match? Is the

asked on February 14, 2017
71. ## Chemistry

The following equation represents the decomposition of a generic diatomic element in its standard state. (1/2)X2(g)--->X(g) Assume that the standard molar Gibbs energy of formation of X(g) is 5.45 kJ·mol–1 at 2000. K and –64.30 kJ·mol–1 at 3000. K.

asked on April 25, 2014
72. ## physics

A ball of mass m = 0.75 kg is thrown straight upward with an initial speed of 8.9 m/s. Plot the gravitational potential energy of the block from its launch height, y = 0, to the height y = 5.0 m. Let U = 0 correspond to y = 0. Determine the turning point

asked on February 13, 2011
73. ## Physics B

A car slows down from 23 m/s to rest in a distance of 85m. What is its constant acceleration? I got -6.224, but a friend was telling me it's -3.11 and that I had to divide by 2. Why is that?

asked on September 12, 2009
74. ## Chemistry

A 0.1300 g iron ore sample was dissolved in hydrochloric acid and the iron was obtained as Fe2+(aq). The iron solution was titrated with Ce4+ solution according to the balanced chemical reaction shown below. After calculation, it was found that 0.0259 g of

asked on March 13, 2009
75. ## Geography

The acceptance of bribes by government officials who manage natural resources is an example of... A.profit maximization. B.productivity. C.environmental regulations. D.corruption. i chose A because that was in the book and it was false

asked on November 23, 2019
76. ## math

1. Which of the following numbers is a rational? A. 4/5 B. square root of 27 C. 4.02002000200002... D. Square root of 31 2. Which type of number is shown below? 0.313311333111... A. repeating decimal B. rational C. irrational D. terminating decimal 3.

asked on September 21, 2016
77. ## trig

An airplane is flying in the direction 148° with an airspeed of u = 920 kilometers per hour. Because of the wind, its groundspeed and direction are v = 820 kilometers per hour and 140°, respectively (see figure). Find the direction and speed of the wind.

asked on November 2, 2015
78. ## Chemistry Buffers

Write reactions showing how each of the following buffers would neutralize added HCl. HF and NaF Express your answer as a balanced chemical equation. Identify all of the phases in your answer. HC2H3O2 and KC2H3O2 Express your answer as a balanced chemical

asked on November 16, 2014
79. ## Math

Webster Aquatic Center offers various levels of swimming lessons year-round. The March 2005 Monday and Wednesday evening lessons included instructions from Water Babies through Adults. The number in each classification is given in the table that follows.

asked on July 4, 2012
80. ## Trig

From a point P on level ground, the angle of elevation of the top of a tower is 27°10'. From a point 23.0 meters closer to the tower and on the same line with P and the base of the tower, the angle of elevation of the top is 51°30'. Approximate the

asked on June 26, 2012
81. ## chemistry

Consider the following reaction: CaCN2 + 3H2O ¨ CaCO3 + 2NH3 105.0 g CaCN2 and 78.0 g H2O are reacted. Assuming 100% efficiency, which reactant is in excess and how much is leftover? The molar mass of CaCN2 is 80.11 g/mol. The molar mass of CaCO3 is

asked on October 31, 2010
82. ## math

Why couldn't the two elephants go swimming together?

asked on March 17, 2009
83. ## Chem

Determine the number of moles of N atoms in 43.5 g of Mg(NO3)2. Textbook answer: 1.43 mol N My answer: 43.5 g Mg(NO3)x x (1 mol Mg(NO3)2/148.313 g Mg(NO3)2) x (2 mol N/1 mol Mg(NO3)2) = .293 Can tell me where i went wrong?

asked on March 8, 2009
84. ## Physics

When a wheel is rotated through an angle of 35 degrees, a point on the circumference travels through an arc length of 2.5 m. When the wheel is rotated through angles of 35 rad and 35 rev, the same point travels through arc lengths of 143 m and 9.0 X 10^2

asked on November 19, 2008
85. ## Chemistry

Consider the following chemical reaction: Cr3+(aq) + 6H2O(l) → [Cr(H2O)6]3+(aq) Would this reaction have a positive or negative entropy of formation?

asked on November 25, 2019
86. ## chemistry

What is the mass of sodium needed to make 2 g of sodium oxide (4Na + O2 → 2Na2O)? Ar values: O = 16, Na = 23. please help I'm really struggling. also please try to explain it to the simplest form because I really don't understand.

asked on March 14, 2019
87. ## algebra

what is the value of 11x^-3y^-1 for x = -1 and y = 2?

asked on March 3, 2019
88. ## Precalculus

you borrow $5,000 from your parents to purchase a used car. The arrangements of the loan are such that you make payments of$250 per month toward the balance plus 1% interest on the unpaid balance from the previous month. (a) Find the first year monthly

asked on February 6, 2018
89. ## Pre Calculus

For a vector $\bold{v}$, let $\bold{r}$ be the reflection of $\bold{v}$ over the line $\bold{x} = t \begin{pmatrix} 2 \\ -1 \end{pmatrix}.$ [asy] unitsize(1 cm); pair O, V, R; O = (0,0); V = (3,1); R = reflect(O,(2,-1))*(V); xaxis(-2,4); yaxis(-3,1);

asked on September 20, 2017
90. ## Maths

In class 8m, there are 27 pupils. There are twice as many boys as girls. How many boys are there?

asked on July 3, 2016
91. ## physics

A plastic rod is rubbed against a wool shirt, thereby acquiring a charge of −4.9 µC. How many electrons are transferred from the wool shirt to the plastic rod? The elemental charge is 1.6 × 10−19 C.

asked on March 10, 2015
92. ## Math

A fence 12ft high runs parallel to a tall building at a distance of 2ft from the building. What is the length of the shortest ladder that will reach from the ground over the fence to the wall of the building?

asked on December 13, 2014
93. ## Math

In first gear, or low gear, an automobile's engine runs about three times as fast as the drive shaft. In second gear, the engine does not have to run as fast; usually it runs about 1.6 times faster than the drive shaft. Finally, in third, or high gear, the

asked on June 17, 2013
94. ## English II

On a proud round cloud in a white high night. A. alliteration B. consonance C. assonance D. limerick

asked on May 1, 2013
95. ## physics 100

Bob, who has a mass of 60 , can throw a 800 rock with a speed of 26 . The distance through which his hand moves as he accelerates the rock forward from rest until he releases it is 1.0 . a) What constant force must Bob exert on the rock to throw it with

asked on October 13, 2012
96. ## physics

A hockey puck slides across the ice at a con- stant speed. Which of the following is true? 1. The puck is moving and thus not in equi- librium. 2. The puck can be considered neither at rest nor in equilibrium. 3. It is in equilibrium. 4. None of these 5.

asked on October 17, 2011
97. ## math

A young man spent 1/4 of his allowance on a movie. He spent 11/18 of the remainder on after-school snacks. Then from the money remaining, he spent \$3.00 on a magazine, which left him 1/24 of his original allowance to put into savings. How much of his

asked on October 9, 2009
98. ## math

Farmer Brown had some animals. One-fourth were horses, one-half were cows, and the rest were pigs. He had 8 pigs. How many animals did he have altogether? I know you would get a common denominator for 1/4 and 1/2 which would be 4 so you would have 1/4+2/4=

asked on February 4, 2009
99. ## Geography

is Christianity the dominant religion in North Africa? true or false? I think it's false because it's Islam right? I just want to be sure

asked on November 23, 2019
100. ## physics

A shot putter throws the shot (mass=7.3kg) with an initial speed of 14.4 m/s at a 34.0 degree angle to the horizontal. Calculate the horizontal distance traveled by the shot if it leaves the athlete's hand at a height of 2.10m above the ground.

asked on October 25, 2018