Question 1181573
z=(x-mean)/sd
a. z=9.7/8.9 and 17.7/8.9 or 1.09 and 1.99.  That probability is 0.1146
b. z=-2.3/8.9 and 2.7/8.9 or -0.26 and 0.30 with probability of 0.2204
check with 2nd VARS2normalcddf(82,90,72.3,8.9) which is more accurate because the z-values above were rounded, But it is only to the fourth decimal place in the first and 0.0008 different in the second. Ask how accurate it should be.
c.80th percentile has a z of 0.8416. (can use 3invnorm(0.80,0,1) to get the z-value
so 0.846=(x-72.3)/8.9
7.49=x-72.3
x=79.8 cm