Answer to Question #264155 in Statistics and Probability for Nathan

Question

The daily revenue of Modern Style Hair Salon is approximately normally distributed with a mean of R7200 and a standard deviation of R1500. 75% of days, the salon makes more than (Rands only no cents)

Answer 1

$P(Z>z)=0.75\to P(Z<z)=0.25)\to z=-0.67.$

$\frac{x-\mu}{\sigma}=-0.67\to x=\mu-0.67\sigma=7200-0.67*1500=6195.$