# 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

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.

3. ## 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

4. ## 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

5. ## Pre Calculus

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

6. ## 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?

7. ## 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.

8. ## 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-

9. ## 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

10. ## 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^+

63. ## 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

64. ## 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

65. ## 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

66. ## 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?

67. ## 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

68. ## 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

69. ## 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

70. ## Math

Find the real part of (sqrt{3} - i)^{2011}.

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.

72. ## 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. :)

73. ## 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

74. ## 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.

75. ## 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

76. ## 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

77. ## 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

78. ## 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.

79. ## 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.

80. ## 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.

81. ## statistics

The distribution of B.A. degrees conferred by a local college is listed below, by major. Major Frequency English 2073 Mathematics 2164 Chemistry 318 Physics 856 Liberal Arts 1358 Business 1676 Engineering 868 9313 What is the probability that a randomly

82. ## 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.

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?

84. ## 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?

85. ## 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

86. ## 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.

87. ## 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.

88. ## 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);

89. ## Maths

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

90. ## 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.

91. ## 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?

92. ## 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

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

94. ## chemistry

Calculate the density of M&M’s given the following data: Mass of 250.0 mL beaker = 197.816 g Mass of beaker and 20 M&M’s = 342.816 g Volume of water in graduated cylinder = 8.0 mL Volume of water in graduated cylinder and 10 M&M’s = 18.5 mL (Points :

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

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.