Homework Problem 10, Due Monday February 25.
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(a) Write and test a function to generate
N random variables which have density

f(x) = .3 * dnorm(x)  + .7 * dlogis(x/1.5)/1.5

(b) Write and test a function to generate N iid 
random variables which have density 

          .2 * exp(-x)            if  x >= 1
       
h(x)  =  ((1-.5*exp(-1))/(2*pnorm(1)-1)) * dnorm(x)
				  if abs(x) < 1
     
	  .3 * exp(x)             if  x <= -1