Question 1012954
z=(x-mu)/sd
z(0.90)=+1.28; because the top 10% occurs at the 90th percentile for z.
1.28=(x-73)/5
5*(1.28)=x-mu
6.4=x-mu
x=79.4

The 16th percentile occurs when z=-0.994
-0.994=(x-mu)/5
-5=x-mu
mu-5=x
x=68