# Posts by john

Total # Posts: 8,287

**math**

A company has a policy of retiring company cars; this policy looks at number of miles driven, purpose of trips, style of car and other features. The distribution of the number of months in service for the fleet of cars is bell-shaped and has a mean of 56 months and a standard ...

*November 30, 2015*

**math**

The average resting heart rate of a population is 89 beats per minute, with a standard deviation of 13 bpm. Find the z-scores that correspond to each of the following heart rates. Round your answers to the nearest hundredth, if necessary. (a) 95 bpm Z= (b) 69 bpm Z=

*November 30, 2015*

**math**

The average resting heart rate of a population is 89 beats per minute, with a standard deviation of 13 bpm. Find the z-scores that correspond to each of the following heart rates. Round your answers to the nearest hundredth, if necessary. (a) 95 bpm Z= (b) 69 bpm Z=

*November 30, 2015*

**math**

Alicia Martin's savings account has a principal of $1,200. It earns 6% interest compounded quarterly for two quarters

*November 30, 2015*

**Statistic**

an insurance policy sells for $700. based on past data, an average of 1 in 80 policyholders will file a $10,000 claim, an average of 1 in 120 policyholders will file a $20,000 claim, and an average of 1 in 200 policyholders will file a $50,000 claim. what is the expected value...

*November 28, 2015*

**Programming**

Declare Integer count For count=1 to 3 Step 2 Display count End For What would the output be?

*November 26, 2015*

**Algebra**

Year Number of Graduates (in millions) 2009 15.4 2010 15.9 2011 16.3 2012 16 2013 15.7 a. Code the years using t = 1 for 2009 and fit a quadratic function to the data with the regression program on your calculator. equation is ________________________________ b. Predict the # ...

*November 25, 2015*

**Physics**

What is the mass of a copper wire that will give a wire, 0.20mm in diameter, a resistance of 400 ohms can you please show me the formulas

*November 25, 2015*

**Physics**

Three charges are located along the x axis as shown in the drawing. The mass of the -1.2 uC is 4.0×10^-9 kg. Determine the magnitude and direction of the acceleration of the -1.2 uC charge when it is allowed to move if the other two charges remain fixed. I need help ...

*November 25, 2015*

**Algebra**

9.The following table gives the number of graduates in health professions in the U.S. for various years. Year Number of Graduates (in millions) 2009 |15.4 2010 |15.9 2011 |16.3 2012 |16 2013 |15.7 a. Code the years using t = 1 for 2009 and fit a quadratic function to the data ...

*November 24, 2015*

**Algebra**

The Yellow Pencil Company sells the best pencils ever made. If the cost of producing x hundred pencils is given by C(x)=0.4x^2-29x+44 and if the revenue generated from the sale of x hundred pencils is R(x)=-0.6x^2+19x. Money is in thousands of dollars. (a) Show all work to ...

*November 24, 2015*

**Algebra**

During the first part of a canoe trip, May paddled 20 km up steam and 20 km back in a total time of 5 hrs. The speed of the river is 3 km/hr. Find May’s speed in still water. Set up the equation first then solve.

*November 24, 2015*

**Algebra**

The Yellow Pencil Company sells the best pencils ever made. If the cost of producing x hundred pencils is given by C x x x ( ) 0.4 29 44 = − + 2 and if the revenue generated from the sale of x hundred pencils is R x x x ( ) 0.6 19 = − + 2 . Money is in thousands of...

*November 24, 2015*

**Algebra**

The distance traveled by an object moving in a straight line is given by s = t2 − 2t, where s is in feet and t is the time in seconds the object has been in motion. How long (to the nearest tenth) will it take the object to move 48 feet?

*November 24, 2015*

**Chemistry**

Why is Hydrogen sulfate amphiprotic?

*November 23, 2015*

**math**

write 2.18 as a mixed number in simplest form

*November 23, 2015*

**Pre-Algebra**

A ball is thrown straight up at 46 feet per second from about 6 feet above the ground. How long will it take for the ball to reach a height of 39 feet?

*November 22, 2015*

**Physics**

Using the data in the table below,determine how many calories are needed to change 100g of solid x at 10degrees celcious to a vapour at 210degrees celcious:thermodynamic constants for substance x: heat of fusion 40,0cal/g heat of vaporization 150,0cal/g melting point 10,0'...

*November 22, 2015*

**Philosophy**

In her book The Beauty Myth author Naomi Wolf argued that women harm themselves when they try to live up to the standards of beauty implied in most commercial advertising. The following excerpt is taken from a World Press Review commentary on Wolf’s work: [S]omething that...

*November 21, 2015*

**science**

A boy complains of stomach pain to his mother. Unable to resolve the issue herself, she takes the boy to the doctor. Which of the following might be a good hypothesis for the stomach pain?The boy fell and hurt his stomach. The boy has an infection and needs antibiotics. The ...

*November 20, 2015*

**functions**

Andrew is 5 years older than Tim. Tim is aged 19. Write an equation for x, where x is the age of Andrew. Solve the equation.

*November 20, 2015*

**Algebra 2**

How do I find z (or any other variable for that matter)? −2z + 6 + 2(z+1) = 14 −2z + 6 + 2z + 2 = 14 8 = 14 I try to solve the equation but end up with this, which is false.

*November 19, 2015*

**Algebra 2**

Solve by Substitution x + 2y + z = 14 y = z + 1 x = -3z + 6

*November 19, 2015*

**Chemistry**

What is the pH of a solution resulting from the addition of 10.0 mL of 0.17 M HCl to 50.0 mL of 0.16 M NH3? Assume the volumes are additive. Kb of NH3 = 1.8 ✕ 10-5.

*November 18, 2015*

**english**

Which revision changes a verb in the sentence to the subjunctive mood? Some colleges require that each potential student completes an essay.

*November 18, 2015*

**Math**

Show that the equation tanθ = sinθ can be written in the form sinθ(1 - 5cosθ) = 0?

*November 18, 2015*

**Physical science**

A train with a mass of 200,000 kg manages to brake to a speed of 3 m/sec before colliding with a truck with a mass of 2,000 kg that is stuck on the track. What speed does the truck move away from the train.

*November 18, 2015*

**EFA**

write a cubic equation whose integral coefficient roots are -5 and radical 2

*November 17, 2015*

**algebra help!**

So the answer 40

*November 16, 2015*

**Algebra**

Divide and reduce to lowest terms wherever possible. 105/ 5+1/4

*November 15, 2015*

**Math homework**

1-(1/6)-(2/5) = (5/6)-(2/5) = ((25-12)/30) = 13/30

*November 12, 2015*

**Integral Calculus - Series**

Find if series is convergent or divergent. Series from n=2 to infinity (4n+7)/(3n^3 -8n)

*November 12, 2015*

**Math**

Thank you

*November 12, 2015*

**Math**

An airplane flys at a constant altitude of 2 miles and a constant speed of 600 miles per hour on a straight course that will take it directly over a kangaroo on the ground. How fast is the angle of elevation of the kangaroo's line of sight increasing when the distance ...

*November 12, 2015*

**math-linear algebra**

Determine which of the following mappings are linear mappings. A. The mapping L defined by L(x_1, x_2 ) = (4x_1- 2x_2, 3 |x_2|). B. The mapping L defined by L(x_1, x_2 ) = (2x_1-3x_2, x_1+4, 5x_2). C. The mapping L defined by L(x_1, x_2, x_3 ) =(x_1, 0 , x_3). D. The mapping L...

*November 11, 2015*

**math-linear algebra**

Determine the standard matrix A of the linear mapping L:R^2-->R^2 that rotates any vector through an angle of 150 degrees in the clockwise direction.

*November 11, 2015*

**math-linear algebra**

Determine the standard matrix D of the linear mapping G: R^2--R^2 that first rotates points clockwise through pi/6 radians and then reflects points through the line x_2=x_1

*November 11, 2015*

**Physics**

Air consists of molecules of several types, with an average molar mass of 28.95g. About how many molecules does an adult who inhales 0.50L of air at sea level take in? The answer should be 1.3x10^22

*November 11, 2015*

**math**

2x - 6 = 20. Add 6 to both sides. 20 + 6 = 26 26÷2 =13

*November 11, 2015*

**math**

[2(X+26)]/2=264/2 X+26=132 X+26-26=132-26 X=106

*November 11, 2015*

**physics**

A puck (mass m1 = 2.20 kg) slides on a frictionless table as shown in the figure below. The puck is tied to a string that runs through a hole in the table and is attached to a mass m2 = 6.6 kg. The mass m2 is initially at a height of h = 6.6 m above the floor with the puck ...

*November 10, 2015*

**physics**

A child of mass 52 kg jumps onto the edge of a merry-go-round of mass 170 kg and radius 1.9 m that is initially at rest as sketched in the figure below. While in the air (during her jump), the child's linear velocity in the direction tangent to the edge of the merry-go-...

*November 10, 2015*

**physics**

The drawing shows a skateboarder moving at 6.88 m/s along a horizontal section of a track that is slanted upward by 37.3 ° above the horizontal at its end, which is 0.741 m above the ground. When she leaves the track, she follows the characteristic path of projectile ...

*November 9, 2015*

**Organic Chemistry 2**

What is the impurity that must be removed from the benzaldehyde reagent before it can be used in this experiment? this is from are Benzil lab

*November 9, 2015*

**Organic Chemistry 2**

Compare the IR spectrum of benzoin ) with the IR spectrum of benzil . Explain how the changes in the important peaks are related to the differences between the two structures.

*November 9, 2015*

**math**

Every cereal box has a gift inside, but you cannot tell from the outside what the gift is. The store manager assures you that 16 of the 58 boxes on the shelf have the secret decoder ring. The other 42 boxes on the shelf have a different gift inside. If you randomly select two ...

*November 8, 2015*

**math**

In a family with 4 children what is the probability of having 1 boy and then 3 girls, in that order? (Exclude multiple births and assume all outcomes are equally likely). In a family with 4 children, what is the probability of having 1 boy and 3 girls, in any order? (Exclude ...

*November 8, 2015*

**math**

A hacker is trying to guess someone's password. The hacker knows (somehow) that the password is 14 characters long, and that each character is either a lowercase letter, (a, b, c, etc), an uppercase letter (A, B, C, etc) or a numerical digit (0, 1, 2, 3, 4, 5, 6, 7, 8, or ...

*November 8, 2015*

**math**

A hacker is trying to guess someone's password. The hacker knows (somehow) that the password is 14 characters long, and that each character is either a lowercase letter, (a, b, c, etc), an uppercase letter (A, B, C, etc) or a numerical digit (0, 1, 2, 3, 4, 5, 6, 7, 8, or ...

*November 8, 2015*

**math**

A couple plans to have three children. What is the probability that. a) they have all boys? b) they have at least one girl?

*November 8, 2015*

**Organic Chemistry 2**

What is the impurity that must be removed from the benzaldehyde reagent before it can be used in this experiment? this is from are Benzil lab in this lab, benzoin condensation of benzaldehyde will be carried out with a biological coenzyme, thiamine hydrochloride, as the ...

*November 8, 2015*

**Organic Chemistry 2**

What is the purpose of adding NaOH ot the reaction? This is the from our Benzil Lab.

*November 8, 2015*

**Organic Chemistry 2**

Compare the IR spectrum of benzoin ) with the IR spectrum of benzil . Explain how the changes in the important peaks are related to the differences between the two structures.

*November 8, 2015*

**Organic Chemistry 2**

Compare the IR spectrum of benzoin ) with the IR spectrum of benzil . Explain how the changes in the important peaks are related to the differences between the two structures.

*November 7, 2015*

**Organic Chemistry 2**

What is the purpose of adding NaOH ot the reaction? This is the from our Benzil Lab.

*November 7, 2015*

**Organic Chemistry 2**

Isolation of crude Benzoind-allow about 5 minutes for the crystals of benzoin to form fully. place the flask, with crystals, into an ice bath for 5-10 minutes. Break up the crystalline mass with a spatula, swirl the flask rapidly and quickly transfer the benzoin to a hirsch ...

*November 7, 2015*

**Organic Chemistry 2**

Procdure. Reaction Mixture-Add 0.3 g of thiamine hydrochloride to a erlenmeyer flask. Dissolve the solid in 0.45 mL of water by swirling the flask. Add 3.0 mL of 95% ethanol, and swirl the solution until it is homogeneous. To this solution add 0.9 mL of an aqueous sodium ...

*November 7, 2015*

**Organic Chemistry 2**

umm in this lab, benzoin condensation of benzaldehyde will be carried out with a biological coenzyme, thiamine hydrochloride, as the catalyst:

*November 7, 2015*

**Organic Chemistry 2**

What is the impurity that must be removed from the benzaldehyde reagent before it can be used in this experiment? this is from are Benzil lab

*November 7, 2015*

**Physics**

The propeller blades of an airplane are 2.4 m long. The plane is getting ready for takeoff, and the propeller starts turning from rest at a constant angular acceleration. The propeller blades go through two revolutions between the fifth and the seventh second of the rotation. ...

*November 7, 2015*

**Math**

9/16 x 2/3 =

*November 5, 2015*

**math 8th grade**

for a project, you need the diagonal fold of a square piece of origami paper to be 10 cm long. to what dimensions do you need to cut the square origami paper?

*November 5, 2015*

**math 8th grade**

a black 8" tile was cut to surround a white 8" tile. what is the perimeter of the design?

*November 5, 2015*

**math 8th grade**

what is the height of an equilateral triangle with an edge of one meter?

*November 5, 2015*

**calculus**

An Olympic athlete is standing at the edge of one side of a 3.7km wide river and wants to reach the point 7.4km downstream just along the edge of the opposite side. For this entire 7.4km stretch, the river is completely straight. The velocity of the current is negligible. The ...

*November 5, 2015*

**Math! Pls Help!**

i need help on that same thing can you put something els up

*November 5, 2015*

**Biology**

0.052

*November 5, 2015*

**chemistry**

To a 100.0 mL solution containing 0.0100 M Ba(NO3)2 and 0.0100 M Pb(NO3)2 was added 101.0 mL of 0.0100 M H2SO4 to provide a slight excess of SO42- relative to Ba2+ in the resulting solution. Assuming that: i) H+ does not bind to SO42- ii) ionic strength effects can be ignored ...

*November 4, 2015*

**Physics**

The propeller blades of an airplane are 2.4 m long. The plane is getting ready for takeoff, and the propeller starts turning from rest at a constant angular acceleration. The propeller blades go through two revolutions between the fifth and the seventh second of the rotation. ...

*November 4, 2015*

**Calculus**

For a cylinder with a surface area of 90, what is the maximum volume that it can have? Round your answer to the nearest 4 decimal places. The volume of a cylinder is πr^2*h and the surface area is 2πrh+2πr^2.

*November 4, 2015*

**physics**

You drop a 1.90 kg book to a friend who stands on the ground at distance D = 11.8 m below with outstretched hands at distance d = 1.42 m above the ground. a)What is the speed of the book when it reaches the hands? b)If we substituted a second book with twice the mass, what ...

*November 3, 2015*

**Algebra 1**

Did you ever find out the answer?

*November 3, 2015*

**Math**

a wrench is dropped by a worker at a construction site. four seconds later the worker hears it hit the ground below. How high is the worker above the ground? (The velocity of sound is 1100 ft/s, and the distance the wrench falls as a function of time is s=6t^2

*November 2, 2015*

**physics**

a block of mass M = 9.9 kg rests on a bracket of mass m = 5.5 kg. the bracket sits on a frictionless surface. the coefficients of friction between the block and the bracket on which it rests are .4 and .3. what is the maximum force that can be applied if the block is not to ...

*November 2, 2015*

**science**

Ana exerts a force of 20 N on a volleyball that has a mass of 0.15 kg. What is the force that the volleyball exerts on Ana?

*November 2, 2015*

**biology**

Determine the effective population size of the current population located on an island. You conduct a census and determine there are about 1500. -Your initial survey indicated that there are 500 juveniles (Smaller, with no horns) on the island. What would you consider the ...

*October 31, 2015*

**Physical science**

Mist graph

*October 29, 2015*

**math**

Ms.Sue can you help me

*October 28, 2015*

**math**

@Ms.Sue

*October 28, 2015*

**math**

what is 10 5/18 - 8 5/6 A. 2 5/9 B. 2 13/18 C.1 4/9 d. 1 11/18 I think It is B?

*October 28, 2015*

**Physics**

When jumping straight down, you can be seriously injured if you land stiff-legged. One way to avoid injury is to bend your knees upon landing to reduce the force of the impact. A 69.3-kg man just before contact with the ground has a speed of 6.94 m/s. (a) In a stiff-legged ...

*October 28, 2015*

**maths**

Fence post are placed 3m apart from each other. How many posts will be placed over a distance of 45m?

*October 27, 2015*

**business statitics**

a) The mean lifetime of a sample of 100 light tubes produced by a company is found to be 1570 hours with standard deviation of 80 hours. Test the hypothesis that the mean lifetime of the tubes produced by the company is 1600 hrs. (7 marks)

*October 27, 2015*

**math**

Find the values of the trigonometric function cot -8/17 sin: sec: tan: cot: I know you use a Pythagorean Identity, sin^2t + cos^2t=1 I got 64/289 for the first one for example and it was wrong.

*October 26, 2015*

**Calculus**

A force of 6 pounds is required to hold a spring stretched 0.2 feet beyond its natural length. How much work (in foot-pounds) is done in stretching the spring from its natural length to 0.6 feet beyond its natural length? could you please explain how. thanks

*October 26, 2015*

**chem - help!**

Different manufacturers claim to have the best antacid. Which of the following tablets would neutralize the most acid for the money? Write a balanced chemical equation along with your answer. a) Rolaids (550 mg CaCO3 and 110 mg Mg(OH) per tablet) - 150 tablets for $9.44 b) ...

*October 26, 2015*

**vectors linear algebra**

The parametric equations for a line L1 are as follows: x = −4−6t y = 2+2t z = 1−4t Let L2 be the line parallel to L1 and passing through the point (−3, −3, −3). Find the point P on L2 whose x-coordinate is −12. P=P(-12, _ , _ ) ?

*October 26, 2015*

**math**

find the sum of the sequence 41+42+43+44+117

*October 25, 2015*

**chem**

Different manufacturers claim to have the best antacid. Which of the following tablets would neutralize the most acid for the money? Write a balanced chemical equation along with your answer. a) Rolaids (550 mg CaCO3 and 110 mg Mg(OH) per tablet) - 150 tablets for $9.44 b) ...

*October 25, 2015*

**physics**

17 23

*October 25, 2015*

**biology**

Which of the following statements best explains the relationship between the mitochondria and the plasma membrane? A. The mitochondria makes proteins that become a part of the plasma membrane. B. The mitochondria makes a gas that the plasma membrane uses. C. The mitochondria ...

*October 25, 2015*

**science**

im confused are these answers incorrect ?

*October 25, 2015*

**math**

1)11.7 so do you round up or no ? either its 11 or 12 2)87.50 ? 3)A

*October 25, 2015*

**math**

6.85 ?

*October 25, 2015*

**math**

Suppose f(t) is the weight (in grams) of a solid sitting in a beaker of water and the solid is dissolving at a rate (in grams/minute) of f'(t)=-4 f(t)(3 + f(t) ). If there is 4 grams of solid at time t=2 minutes, use a linear approximation to estimate the solid's ...

*October 24, 2015*

**math**

Suppose f(t) is the weight (in grams) of a solid sitting in a beaker of water and the solid is dissolving at a rate (in grams/minute) of f'(t) =-4 f(t)(3 + f(t) ). If there is 4 grams of solid at time t=2 minutes, use a linear approximation to estimate the solid's ...

*October 24, 2015*

**math**

Suppose N(t) denotes a population size at time t where the dN/dt=0.03 N(t). If the population size at time t=4 is equal to 100, use a linear approximation to estimate the size of the population at time t=4.1.

*October 24, 2015*

**math**

A cup of coffee at 173 degrees is poured into a mug and left in a room at 72 degrees. After 6 minutes, the coffee is 137 degrees. Assuming that Newton's Law of Cooling applies: After how many minutes will the coffee be 100 degrees?

*October 24, 2015*

**math**

Suppose f(x)=ln x. (a) Find the linear approximation of f at a=1. L(x)= (b) Use the linear approximation to estimate ln 1.27. ln1.27=

*October 24, 2015*

**Chemistry**

Do positive ions or the negative ions cause the change in flame color ? Explain why and give on example.

*October 23, 2015*