Question

The number of books borrowed from a library each week follows a normal distribution. When a sample is taken for several weeks, the mean is found to be 190 and the standard deviation is 30.
There is a _____% chance that more than 250 books were borrowed in a week.
A. 99.7
B. 95
C. 13.5
D. 2.5
3.

Answer 1

Solution: There is a 2.5% chance that more than 250 books were borrowed in a week.

Explanation:

We are given:

$\mu=190, \sigma =30$

$P(x>250)$

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

       $=\frac{250-190}{30}$

       $=\frac{60}{30} =2$

Therefore, we have to find $P(z>2)$. Using the standard normal table, we have:

$P(z>2)=0.023 \approx 0.025 or 2.5\%$

Therefore, the correct option is D. 2.5

Answer 2

Answer:

D. 2.5%

Step-by-step explanation: