A set of data has a normal distribution with a mean of 5.1 and a standard deviation of 0.9. Find the percent of data between 4.2 and 5.1.
Answer: The correct option is B) about 34%
Proof:
We have to find

To find
, we need to use z score formula:
When x = 4.2, we have:


When x = 5.1, we have:


Therefore, we have to find

Using the standard normal table, we have:
=


or 34.13%
= 34% approximately
Therefore, the percent of data between 4.2 and 5.1 is about 34%