Most popular questions and responses by Cynthia
  1. statistics

    the life spans of three randomly selected tires are 31,400 miles, 40,600 miles and 36,000 miles. Using the empirical rule, find the percentile that corresponds to each life span.

    asked on September 8, 2013
  2. math

    an open box contains 80cm^3 and is made from a square piece of tinplate with 3cm squares cut from each of its 4 corners. Find the dimensions of the original piece of tinplate.

    asked on September 20, 2009
  3. Chemistry

    If the percent yield was 81.5%, how many grams of aluminum were used to prepare 20.0 g of potassium alum?

    asked on February 29, 2012
  4. Chemistry

    How many moles and how many grams of potassium alum, KAl(SO4)2 · 12 H2O, can be prepared from 5.00 g of aluminum?

    asked on February 29, 2012
  5. Trig

    Find the exact value of tan 5pi/12 using the half-angle identity.

    asked on October 15, 2011
  6. Life orientation

    What are the impact of risk behaviour?

    asked on August 18, 2018
  7. Chemistry

    Calculate the percent yield of alum if you obtained 75.0 g of potassium alum from 5.00 g Al.

    asked on February 29, 2012
  8. math (combination)

    A woman has 11 close Friend. Find the number of ways she can invite 5 of them to dinner if a. but where 2 of the friends are married and will not attend separately b. where 2 of the friend will not attend together the answer to a. 210 b. 252 Please

    asked on December 30, 2010
  9. Physics

    A box rests on the back of a truck. The coefficient of static friction between box and bed of the truck is 0.255. (a) When the truck accelerates forward, what force accelerates the box? A)the inertial force B)gravity C)centripetal force D)the friction

    asked on March 8, 2012
  10. statistics

    A study found that 81% of households in the United States have computers. Of those 81%, 92% have Internet access. Find the probability that a U.S. household selected at random has a computer and has Internet access.

    asked on February 7, 2013
  11. chemistry

    0.5123 g KHP sample was dissolved in about 25 mL of distilled water, and titrated to the phenolphthalein endpoint with 28.75 mL of a sodium hydroxide solution. Calculate the molar concentration of the hydroxide solution

    asked on October 16, 2010
  12. Language arts

    What is the principle part of the italicized verb in this sentence (suppressed) from "The Story-Teller"? The aunt suppresed a gasp of admiration. A. Present B. Present participle C. Past D. Past participle I think it's D.....But im lost on the meanings of

    asked on September 15, 2015


    asked on March 15, 2017
  14. math

    bobs monthly phone bill is made up of a 10.00 fee plus $0.05 per min.bobs phone bill for july was 22.00 write an equation to model the situation using m to represent the number of min. solve the bequation to determine the number of phone mins.bob used in

    asked on March 3, 2015
  15. Science

    What is the similarities between conduction and radiation What is the similarities between convection and radiation

    asked on May 17, 2015
  16. Chemistry

    The melting point of aspirin : 128-137Celsius degree. The melting point of the crude aspirin was measured to be 128 Celsius degree. What does it indicate about the purity of the product?

    asked on December 5, 2010
  17. physics

    A ball starts from rest and rolls down a hill with uniform acceleration, traveling 200m during the second 4.8s of its motion. How far did it travel the first 4.8 seconds

    asked on September 16, 2014
  18. Chemistry

    Calculate the amount in moles and the mass in grams of KOH needed to convert 1.50 g of aluminum to KAl(OH)4. Balanced equation = 2 Al (s) + 2 KOH (aq) + 6 H2O (l) ¨ 2 KAl(OH)4 (aq) + 3 H2 (g)

    asked on February 29, 2012
  19. Chemistry

    A 0.250g smaple of magnesium-aluminum alloy dissolves completely in an excess of HCl(aq). When the liberated H2(g) is collected over water at 29C at 752torr, the volume is found to be 297mL. The vapor pressure of water at 29C is 30.0torr. What is the mass

    asked on October 9, 2011
  20. geography

    Social effects of poor service delivery.

    asked on May 15, 2016
  21. Advanced accounting

    The balance sheets of Petrello Company and Sanchez Company as of January 1, 2011, are presented below. On that date, after an extended period of negotiation, the two companies agreed to merge. To effect the merger, Petrello Company is to exchange its

    asked on November 15, 2010
  22. Chemistry

    What mass of oxalic acid dihydrate , H2C2O4•2H2O, is required to prepare 220.0 ml of a 1.28 M solution of oxalic acid ?

    asked on February 22, 2012
  23. Chemistry

    In basic solution, H2O2 oxidizes Cr+3 to Cro4^-2 and is reduced to OH-. What is the balanced equation?

    asked on February 22, 2012
  24. Chemistry

    A student titrated 1.852 g of a mixture containing potassium hydrogen phthalate, KHP....? A student titrated 1.852 g of a mixture containing potassium hydrogen phthalate, KHP, with 0.163 M NaOH solution. She recorded an initial buret reading of 0.84 mL and

    asked on March 7, 2012
  25. new era

    the third term of an AP is 5 while the 7th term is 13,find the 30th term of the AP

    asked on August 11, 2015
  26. math

    Mrs. Bollo's second grade class of thirty students conducted a pet ownership survey.results of the survey indicated that 8 students own a cat, 15 students own a dog and five students owned neither a cat or a dog. how many of the students surveyed owned

    asked on March 13, 2015
  27. Chemistry

    Oxygen has a boiling point of 90K, and nitrogen has boiling point of 77K. Which is a liquid and which is a gas at 80K? I tried to look into the phase diagrams, but I still don't understand. Can somebody please help and explain to me??? THANKS A LOT!!!

    asked on July 10, 2011
  28. Language arts Participial Phrase

    In the following sentence, what word does the participial phrase modify? Everyone in the annex heard her screaming loudly everyone annex heard her

    asked on April 25, 2016
  29. Early Childhood

    A preschooler with a vocabulary of about 4,000 words would be considered: A. a slow developer. B. advanced. C. very advanced.

    asked on February 19, 2015
  30. chemistry

    A particular coal contains 2.55% sulfur by mass. When the coal is burned, it produces SO2 emissions which combine with rainwater to produce sulfuric acid. Determine how much sulfuric acid (in metric tons) is produced by the combustion of 1.1 metric ton of

    asked on June 23, 2010
  31. Physics

    Trying to be on time for class, a girl moves at 2.4 m/s down a 52 m-long hallway, 1.2 m/s down a much more crowded hallway that is 79 m long, and the last 25 m to her class at 3.4 m/s. How long does it take her to reach her class?

    asked on September 18, 2012
  32. Chemistry

    The enthalpy of combustion of benzoic acid is –26.4 kJ/g. What is the enthalpy of combustion expressed in joules per kilogram?

    asked on January 18, 2012
  33. geometry

    The circumference of a circle is approximately 28.26 cm. Find its diameter and radius

    asked on November 2, 2010
  34. Physics

    A 1-m-tall barrel is closed on top except for a thin pipe extending 6.0 m up from the top. When the barrel is filled with water up to the base of the pipe (1 m deep) the water pressure on the bottom of the barrel is 10 kPa. What is the pressure on the

    asked on November 6, 2015
  35. IPC

    If the specific heat of water is 1.0 calorie/gram°C, how many calories are required to raise 500 grams of water 10.0°C?

    asked on November 18, 2014
  36. Chemistry

    Calculate the volume (in mL) of 9.0M H2SO4 that you would need to convert 0.070 moles of KAl(OH)4 to K2SO4 and Al2(SO4)3 according to the following equation: 2 KAl(OH)4 + 4 H2SO4->K2SO4 + Al2(SO4)3 + 8 H2O

    asked on February 29, 2012
  37. physics

    a bimetallic compound strip of brass and iron is 10cm long at 20C. When heated over a Bunsen burner flame the temperature of the brass rises to 800C and the iron to 750C. Calculate the difference in lengths of the iron and brass. (Ignore the bending

    asked on April 21, 2009
  38. Physics

    the velocity of s stationary wave in a sring is given by te relation V=K^x T^y e^z where k is the constant calculate the value of x and y?

    asked on June 12, 2019
  39. Chemistry

    when 2 moles of potassium chlorate crystals decompose to potassium chloride crystals and oxygen gas at a constant pressure and temperature, 78.0 kj of heat is given off. write a thermodynamic equation for this reaction.I don't know how to set up the

    asked on October 16, 2014
  40. Chemistry

    A student must prepare 2.00 L of 0.100 M Na2CO3 (106 g/mol) Which is the best procedure for preparing this solution ?

    asked on February 22, 2012
  41. Psychology

    How does biological and environmental factors shape our cognitive processes?

    asked on December 6, 2012
  42. Physics

    A fire helicopter carries a 520-kg bucket of water at the end of a 20.0-m long cable. Flying back from a fire at a constant speed of 40.0 m/s, the cable makes an angle of 38.0° with respect to the vertical. Determine the force exerted by air resistance on

    asked on March 8, 2012
  43. chemistry

    25.0g of 5.0% (by mass) acetic acid solution are titrated with 0.300 M NaOH. What volume of NaOH will be needed to neutralize this sample?

    asked on May 28, 2010
  44. Chemistry

    The concentration of Pb+2 in a sample of wastewater is to be determined by using gravimetric analysis. To a 100.0-mL sample of the wastewater is added an excess of sodium carbonate, forming the insoluable lead(II)carbonate (267.2092 g/mol) according to the

    asked on February 22, 2012
  45. physics

    You exert a force of 455N in pulling 15.0m of rope using a pulley system to lift a 935N object 5.0m. What is the efficiency of the pulley system? Please help, I appreciate it a lot.

    asked on June 13, 2009
  46. Chemistry

    Zn metal was allowed to react with hydrochloric acid to produce hyrdogen gas.This gave a total of 555mL of gas collected over water at 20C and a pressure of 747mm of Hg. How many moles of hydrogen were collected? The vapor pressure of water at 20C is 18mm

    asked on March 5, 2012
  47. Chemistry

    A 30.00-mL sample of weak acid is titrated with 0.0167 M NaOH. At the endpoint , it is found the 40.35 mL of titrant was used. What was the concentration of the weak acid ?

    asked on February 22, 2012
  48. waves and sound

    1-A tunning fork has a frequency of 440Hz. The string of a violin and this tuning fork, when sounded together, produce a beat frequency of iHz. From these two pieces of information alone, is it possible to determine the exact frequency of the violin

    asked on May 17, 2009
  49. Calculus

    Find the centroid of the area bounded by the parabola y = 4 - x^2 and the x-axis. A. (0,1.6) B. (0,1.7) C. (0,1.8) D. (0,1.9) Find the average value of the function i=15(1-3^-1/2t) from t=0 to t=4. A. 7.5(1+e^-2) B. 7.5(2+e^-2) C. 7.5(2-e^-2) D.

    asked on August 7, 2012
  50. Math (combination/permutation)

    Question 1: There are 12 students in a class. Find the number of ways that 12 studenets can take 3 different tests if 4 students are to take each test. Question 2 Find the number of ways 12 students can be partitioned into 3 teams A, B, C, so that each

    asked on December 30, 2010
  51. Calculus

    1. Locate the absolute extrema of the function f(x)=cos(pi*x) on the closed interval [0,1/2]. 2. Determine whether Rolle's Theorem applied to the function f(x)=x^2+6x+8 on the closed interval[-4,-2]. If Rolle's Theorem can be applied, find all values of c

    asked on October 30, 2012
  52. physics

    two people are pushing a car of mass 2000kg. if they each push with a force of 320N at an angle of 15degrees to each side of the car, calculate the acceleration of the car, assuming no resistance... please help

    asked on March 11, 2009
  53. Statistics

    are the following statements, Ho:=10 and Ha:equal to or less than, a valid pair of null and alternative hypothesis?assume that in a hypothesis test with null hypothesis Ho : u = 12.0 at a = 0.10, that a value of 16.0 for the sample mean results in the null

    asked on November 19, 2011
  54. statistics

    1. If we select a birth at randam, what is the probability the mother is 19 years of age or younger. 2. What is the probability she is 30 years of age or older. 3. What is the expected age of the mother at birth. 4. What is the variance of mother's ages

    asked on June 16, 2008
  55. Chemistry

    What how can I calculate the amount in moles and the mass in grams of KOH needed to convert 1.50 g of aluminum to KAl(OH)4. Balanced equation = 2 Al (s) + 2 KOH (aq) + 6 H2O (l)->2 KAl(OH)4 (aq) + 3 H2 (g) Please show steps ..

    asked on February 29, 2012
  56. chemistry

    why is 1mol of so3 gas higher in entropy than so2 gas

    asked on August 22, 2011
  57. Maths

    Find correct to the nearest degree, the angle between p=12i - 5j and q=4i + 3j? I need solvings please?

    asked on June 12, 2019
  58. Chemistry

    A quantity of 0.020 mole of a gas initially at 0.050 L and 20 degrees Celsius undergoes a constant-temperature expansion until its volume is 0.59 L. Calculate the work done (in joules) by the the gas if it expands (b) pressure of 0.20 atm. (C) If gas in

    asked on December 28, 2010
  59. Chemistry

    Determine the molarity of a sodium hydroxide solution? if 37.34 mL of it are required to neutralize 1.922 g of citric acid. balanced equation- 3NaOH(aq)+H3C6H5O7-->3H2O(l)+NaC6H5O7(aq… ***Plesae show steps.

    asked on March 7, 2012
  60. algebra

    kyle's credit bill is $360. kyle sends a check to the credit card company for $70, charges another $109 in merchandise, and then pays off another $231 of the bill. how much does kyle owe the company?

    asked on January 23, 2008
  61. calculus

    6.A manufacturer of DVD players has been selling 800 each week at 150$each. From a market survey it is discovered that for each $5 reduction in price, they will sell an extra 40DVD players each week. a)What is the demand function? b)How large a reduction

    asked on November 23, 2010
  62. science

    Is a gelatin dessert a solution, a suspension or a colloid? I think it is a suspension. Thanks you. The ingredients of gelatin are completely soluble in water and the end product is clear and transparent. It is a solution, in my opinion.

    asked on June 10, 2007
  63. chemistry

    If 24.7 of 0.250 M NaOH solution are needed to neutralize 19.8 mL of H2SO4 solution, what is the molarity of the H2SO4?

    asked on May 28, 2010
  64. Pengana college of health science and technology

    Shown that alpha =3alpha and beta =2alpha

    asked on April 30, 2019
  65. math

    The normal to the curve y = ax^1/2 + bx at the point where x = 1 has a gradient 1 and intercepts the y-axis (0,-14). Find a and b

    asked on October 3, 2016
  66. Chemistry

    Calculate the amount in moles and the mass in grams of KOH needed to convert 1.50 g of aluminum to KAl(OH)4. Balanced equation = 2 Al (s) + 2 KOH (aq) + 6 H2O (l)->2 KAl(OH)4 (aq) + 3 H2 (g)

    asked on February 29, 2012
  67. Calculus

    A team has been working to convert diesel-powered cars to run just as efficiently on used cooking oil! They want to compare the mileage and speed of their prototype with that of the diesel-powered car. The prototype is 100 meters south of an intersection,

    asked on August 1, 2011
  68. Math

    A 3-mile cab ride cost $3.00. A 6-mile cab ride cost $4.80. Find a linear equation that models cost c as a function of distance d

    asked on March 31, 2010
  69. physics

    the speed of a transverse wave on a string is 450m/s while the wavelength is 0.18m. The amplitude of the wave is 2.0mm. How much time is required for a particle of the string to move a total distance of 1.0km.... The thing that confuses me about this

    asked on May 6, 2009
  70. Chemistry

    What is the net ionic equation for the reaction that occures between nitrouse acid and strontium hydroxide ?

    asked on February 22, 2012
  71. Health of young children

    A teacher is in a prime position to observe children because A.the teacher sees children in relation to other children of the same age. B. the teacher sees each child for fewer hours than the parent and can, therefore be objective. C.he or she is often

    asked on March 25, 2009
  72. Math

    If no digit may be used more than once, how many 2-digit numbers can be formed using only the digits 5, 6, 3, and 2?

    asked on February 19, 2016
  73. think tac toe 2 adding and subracting decimals 2.

    Tim tracked the change in outside temperature one afternoon. He record a temperature of 98.3 degrees at noon. Bathe temperature then rose 5.32 degrees f over the next four hours at 5:00 pm. Tim recorded a temperature change of 108.57 degrees F, How did the

    asked on November 27, 2015
  74. chemistry

    How many 400-mg aspirin tablets can be made from 40.0-kg of aspirin?

    asked on January 18, 2012
  75. Physics

    A 6 µC charge is placed at the origin and a second charge is placed on the x-axis at x = 0.34 m. If the resulting force on the second charge is 4.0 N in the positive x-direction, what is the value of its charge?

    asked on July 14, 2011
  76. chemistry

    Chlorine dioxide, ClO2, has been used as a disinfectant in air conditioning systems. It reacts with water according to the following equation. ... HCl If 142.0 g of ClO2 is mixed with 33.0 g of H2O, how many grams of which reactant remain if the reaction

    asked on June 29, 2010
  77. physics

    a bicyclist is coasting on level ground at 32.35m/s. The bicyclist coasts up an incline of 20.5m at a 30degree angle. How fast is the bicyclist traveling when he grabs the limb?

    asked on April 8, 2009
  78. math

    The equation of a circle with centre O(0,0) is x^2+y^2=40. The points A(-2,6) and B(-6,-2) are endpoints of chord AB. DE right bisects chord AB at F. a)Verify that the centre of the circle lies on the right bisector of chord AB. b)Find the distance from

    asked on October 9, 2008
  79. Algebra

    I don't have a close about this question !!!!!!!! It takes you 3 hours to drive to a concert 135 miles away. You drive 55 miles per hour on highways and 40 miles per hour on the rest of the roads. How many miles do you drive on highways? The rest of the

    asked on January 3, 2016
  80. Precalculus

    A barn has 150 feet of fencing and there are 3 rectangular corrals of identical dimensions along the back wall of the barn. The sides of each corral are attached to the barn and fencing is not needed along the back wall of the barn. If each corral is 30

    asked on October 8, 2012
  81. Chemistry

    A student must prepare 2.00 L of 0.100 M Na2CO3 (106 g/mol) Which is the besst procedure for preparing this solution ?

    asked on February 22, 2012
  82. calculus

    An athlete is running around a circular track of radius 50 meters at the rate of 5 meters per second. A spectator is 200 meters from the center of the track. How fast is the distance between the two changing when the runner is approaching the spectator and

    asked on January 11, 2011
  83. math

    express 2,750,389 in scientific motion

    asked on September 13, 2008
  84. Chemistry

    Using the van der Waals equation, determine the pressure of 436.0g of SO2(g) in a 7.30-L vessel at 725k.? For SO2(g), a=6.865L^2•atm/mol^2 and b=0.05679L/mol. (R=0.0821L•atm/(K•mol))

    asked on March 5, 2012
  85. Earth Science

    How is the local hydrologic cycle affected by the practice of drawing drinking water from a river and then returning sewage to the same river? Can anyone please help?????? THANKS A LOT!!!!!

    asked on July 20, 2011
  86. chemistry help plz

    A potassium permanganate solution containing 1.58g of KMnO4 per liter is added into 5 ml of an acidified iron (||) sulfate solution. Decolorizing of KMnO4 solution has been added .Calculate the mass of FeSo4.7H2O which has been dissolved in one liter of

    asked on January 17, 2016
  87. Chemistry

    How many grames of lithium nitrate LiNO3 (68.9 g/mol) are required to prepare 174.1 mL of a 0.698 MLiNO3 solution ?

    asked on February 22, 2012
  88. Structural Design, Part 2

    The structural technique that includes long vertical studs running from the sill plate to the second floor roof frame is called Frame

    asked on January 20, 2011
  89. mathvariation 2(steve,reiny,reed) pls I need help!

    the force E needed to make a machine pull a load is partly constant and partly varies as the load to be pulled itself.when the load is 20g,the force needed is 1.4n,where as the force needed for 30g load is 2N. Find the: A)law connecting the load and the

    asked on April 30, 2017
  90. Science HELP PLEASE!!!

    I cant get this stupid question, this is disgusting and I just want to get this over with. What the word for when blood rushes towards your !@#$%^& and gets bigger. A. Erection B. Sperm C. !@#$%^& D. Puberty

    asked on April 18, 2016
  91. auguta tech

    Assume that a set of test scores is normally distributed with a mean of 100 and a standard deviation of 20. Use the 68-95-99.7 rule to find the following quantities: a. Percentage of scores less than 100=50 percent b. Relative frequency of scores less than

    asked on April 17, 2010

    A 5-mile cab ride costs $9.30. A 11-mile cab ride costs $17.70. Find a linear equation that models cost c as a function of distance d.

    asked on March 31, 2010
  93. physics

    An unknown substance with a mass of 300 g absorbs 1000 j of heat while undergoing a temperature increase of 15 degrees c. What is the specific heat of the unknown substance ?

    asked on January 23, 2015
  94. English 101

    memo given in which there was no punctuation...only sentences. Please let me know if I have put the semicolon, etc in right place and if third shift should be hyphenated. Thanks!!! Our production plant has made the decision to run third shift and weekends

    asked on June 21, 2013
  95. Finance

    You own a portfolio that has $1500 invested in Stock A and $2,600 invested in Stock B. If the expected returns on these stocks are 11.1 percent and 16.7 percent, respectively, what is the expected return on the portfolio?

    asked on November 25, 2012
  96. Math (combination/permutation)

    Question 1: There are 12 students in a class. Find the number of ways that 12 studenets can take 3 different tests if 4 students are to take each test. Question 2 Find the number of ways 12 students can be partitioned into 3 teams A, B, C, so that each

    asked on December 30, 2010
  97. CHM101

    Alkali metals can be used for all but one of the following

    asked on July 19, 2018
  98. Physics

    You have a boat that is capable of moving at 10.4 m/s through still water. You wish to cross a river that flows due west at 2.8 m/s. At what numerical compass heading must you pilot your boat so that you will reach a destination that is due south of your

    asked on December 11, 2015
  99. physics

    an object of mass 10kg moves in a circle of radius 13m of uniform speed of 43m\s a) calculate the angular velocity b) the centripetal force

    asked on November 8, 2015
  100. chemistry

    I am very confused about hybridization in general. Please give an explanation on how to do this. Which of the following pairs of atomic orbitals of adjacent nuclei can overlap to form a sigma bond? a pi bond? or no bond at all? a) 1s and 1s b) 1s and 2px

    asked on January 8, 2011


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