Key to Practice Midterm III

Problem 1

A)  1/4

B)  1/4000 ln[y/(4000-y)]

Problem 2

In 7 years

Problem 3

A)  29.273

B)  90

Problem 4

A.  We can do the integral to show its 1.  Also note that the pdf is positive for all x.

B.  4

C.  Var = 16, Standard Deviation = 4

D.  2.77

Problem 5

A.  y' = C₂ e^x , y'' =   C₂ e^x  Substituting back in we get 0.

B.  y = 1 + e^x

Problem 6

(x^3/2 + k)^2/3