algebra 2 z table word problem

Question

The scores on the statistics class final exam follow a normal distribution, with a mean of 80 and a standard deviation of 5. What percent of students scored 90 or better?

Answer 1

1) Calculate the z-score for a score of 90. The formula is:

z = (x-μ)/σ

where x is the data point (90), μ is the mean (80) and σ is the standard deviation (5).

2) Look up the percentile for the z-score you got in a z-score table. There's probably one

in your math text. You can also look one up on-line.

3) The percentile you get from the table is the percent of students who scored less than 90.

The percent who scored 90 or better is 1 - the percentile.