Question 1160711
z=(x-mean)/sigma/sqrt(n), and SE is 10/sqrt(25)=2
so this becomes a normal diet with mean 80 and sd 2
a. greater than 78 is a z>-1 or prob. 0.8413
b. between 79 and 85 is z > -0.5 and +2.5 or probability 0.6853
c. z less than 2.5 is probability 0.9938.