Answer
It would be unusual for a sixth-grade student to read more than 200 words per minute. This is because the probability of such an event happening is 0.0009, which is much below 0.05.
Work Step by Step
Want to find $P(x > 200)$
i) Convert 200 to a z-score
z = $\frac{x - \mu}{\sigma}$
z = $\frac{200 - 125}{24}$
z $\approx$ 3.13
ii) $P(z > 3.13)$
= $ 1 - P(z < 3.13)$
= $ 1- 0.9991$
= 0.0009
$P(x > 200) = P(z > 3.13) = 0.0009$
