Question 1068945
80% = 0.8
From standard normal table
P(Z > -0.84) = 0.8
Z = (x - mean)/sd
x = Z * sd = mean
When Z = -0.84, then 
x = -0.84 * 15 + 120
= 107.4
Answer: (b) 107.4
Email: trsomas23@gmail.com
Skype: sahay.avinash