# Posts by Help please.

Total # Posts: 6

**calculus**

The proprietor of Carson Hardware Store has decided to set up a sinking fund for the purpose of purchasing a computer 2 yr from now. It is expected that the purchase will involve a sum of 40000 dollars. The fund grows at the rate of dA/dt= rA+P where A denotes the size of the ...

*April 25, 2012*

**calculus**

The Institute finds that the average student taking Elementary Shorthand will progress at a rate given by dQ/dt=k(80-Q) in a 20 -wk course, where Q(t) measures the number of words of dictation a student can take per minute after t wk in the course. If the average student can ...

*April 21, 2012*

**calculus**

The population of a certain community is increasing at a rate directly proportional to the population at any time t. In the last yr, the population has doubled. How long will it take for the population to triple? Round the answer to the nearest hundredth, if necessary.

*April 21, 2012*

**calculus**

An open rectangular box having a volume of 256 is to be constructed from a tin sheet. Find the dimensions of such a box if the amount of material used in its construction is to be minimal. Hint: Let the dimensions of the box be x by y by z . Then, xyz=256 and the amount of ...

*March 19, 2012*

**calculus**

Determine whether the statement is true or false. If it is true, explain why it is true. If it is false, give an example to show why it is false. a- if f is a function of x and y and a is a real number, then f(ax, ay)= af(x,y). b- if fx(a,b) < 0, then f is decreasing with ...

*March 11, 2012*

**calculus**

evaluate the improper integral whenever it is convergent ∫0,-00 1/(4-x)^(3/2) dx

*March 4, 2012*

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