Question

College students average 8.6 hours of sleep per night with a standard deviation of 35 minutes. If the amount of sleep is normally distributed, what proportion of college students sleep for more than 9.6 hours? _

Answer 1

Answer:

4.27%

Step-by-step explanation:

We have been given that college students average 8.6 hours of sleep per night with a standard deviation of 35 minutes. We are asked to find the probability of college students that sleep for more than 9.6 hours.

We will use z-score formula to solve our given problem.

$z=\frac{x-\mu}{\sigma}$

z = z-score,

x = Random sample score,

$\mu$ = Mean,

$\sigma$ = Standard deviation.

Before substituting our given values in z-score formula, we need to convert 35 minutes to hours.

$35\text{ min}=0.58\text{ Hour}$

$z=\frac{9.6-8.6}{0.58}$

$z=\frac{1}{0.58}$

$z=1.72$

Now, we need to find $P(z>1.72)$.

Using formula $P(z>a)=1-P(z<a)$, we will get:

$P(z>1.72)=1-P(z<1.72)$

Using normal distribution table, we will get:

$P(z>1.72)=1-0.95728$

$P(z>1.72)=0.04272$

$0.04272\times 100\%=4.272\%$

Therefore, 4.27% of college students sleep for more than 9.6 hours.