1) The rate of growth of a certain cell culture is proportional to its size. In 10 hours a population 0f 1 million cells grew to 6 million.How large will the cell culture be after15 hours?

2) A sample of radioactive material disintegrates from5 to4 grams in150 days. After how many days will just1 gram remain?

3) Find the present value of$7,000to be received in7 years, if money may be invested at6.4% with interest compounded continuously.

4) Find all functionsf(x) with the following properties.

f(x)=square root of (x) +1, f (25) =0

5) Use a Riemann sum to approximate the area under the graph off(x)=x2on the interval4x0 usingn=4

subintervals with the selected points as the midpoints.

6) Find the area of the region between the curve and thex-axis.

f(x)=36x2, from 8 to 8

7) Find the area of the region enclosed by the curves between their intersections.

y=x6and y=8x³

8) Determine the average value off(x) over the interval fromx=a tox=b, wheref(x)=(1/x) , a= (1/10) ,

andb=10.