Let X1 be the sample mean based on a sample of size 25 drawn
     Let X1 be the sample mean based on a sample of size 25 drawn from a normal distribution with mean 8 and variance 16. Let X2 be the sample mean based on 
  
  Solution
a and b follow a normal distribution
c and d follow a standard normal disribution (With mean 0 and standard deviation 1)
e follows a t distribution
f follows a standard t distribution, with mean 0 and standard deviation 1

