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

$$P(X>x)=1-P(Z\leq\dfrac{x-7200}{1500})=0.75$$

$$\dfrac{x-7200}{1500}=-0.674490$$

$$x=7200-0.674490(1500)$$

$$x=R6188$$