# Cynthia

Most popular questions and responses by Cynthia-
## 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* -
## 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* -
## 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* -
## 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* -
## Trig

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

*asked on October 15, 2011* -
## Life orientation

What are the impact of risk behaviour?

*asked on August 18, 2018* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## CHEMISTRY

WHY A CONICAL FLASK CONTAINING A HOT SOLUTION IS NOT TIGHTLY STOPPERED TO PREVENT SOLVENT LOSS DURING COOOLING.

*asked on March 15, 2017* -
## 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* -
## Science

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

*asked on May 17, 2015* -
## 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* -
## 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* -
## 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* -
## 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* -
## geography

Social effects of poor service delivery.

*asked on May 15, 2016* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## geometry

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

*asked on November 2, 2010* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## Psychology

How does biological and environmental factors shape our cognitive processes?

*asked on December 6, 2012* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## chemistry

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

*asked on August 22, 2011* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## Pengana college of health science and technology

Shown that alpha =3alpha and beta =2alpha

*asked on April 30, 2019* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## Chemistry

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

*asked on February 22, 2012* -
## 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* -
## 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* -
## 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* -
## chemistry

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

*asked on January 18, 2012* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## math

express 2,750,389 in scientific motion

*asked on September 13, 2008* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## 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* -
## ALGEBRA

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* -
## 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* -
## 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* -
## 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* -
## 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* -
## CHM101

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

*asked on July 19, 2018* -
## 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* -
## 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* -
## 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*