Scores on a standardized test are normally distributed with a mean of 550 and a standard deviation of 45.

Approximately what percent of students scored between 560 and 580?

16%

25%

33%

49%

kikidylm Feb 17, 2020

#1**+1 **

[ 560 -550] / 45 = .222

Using a table of z scores....the % associated with a z score of .22 ≈ 58.7%

[ 580 - 550 ] / 45 = 30 / 45 = .66

Again....using a z score table the % associated with a z score of .66 ≈ 74.5%

So.....the % scoring between 560 and 580 ≈ [ 74.5 - 58.7 ] ≈ 15.8% ≈ 16%

CPhill Feb 17, 2020