Question

The scores on a test are normally distributed with a mean of 19 and a standard deviation of 5

What score would a student need to be in the top 15%

What score would a student need to be in the 92th percentile

Answer 1

24.18 is the required score to get into the top 15%.

26.03 is required to get into the 92nd percentile.

Explanation:

On a TI-84 calculator:

You can use the invNorm function to calculate the point at a given percentage on a normal model

invNorm(area, mean, sd, tail)

Plug in the values and calculate:

invNorm(0.15, 19, 5, RIGHT)

24.18 is the required score to get into the top 15%.

92nd percentile means that this score is better than 92% of scores

Plug in values and calculate:

invNorm(0.92, 19, 5, LEFT)

26.03 is required to get into the 92nd percentile.