Question

Assume that the time a student stays in School is normally distributed with a mean of 5 hours and a standard deviation of 0.5 hours. Every day, Ian stays in School for 5.5 hours. What proportion of students stays less than 5.5 hours?

Answer 1

$\mu = 5 \\ \sigma=0.5 \\ P(X<5.5) = P(Z< \frac{5.5-5.0}{0.5}) \\ = P(Z< 1) \\ = 0.8413$

(Using Z distribution table)