Use technology or a z-score table to answer the question. the scores on a memory test are normally distributed with a mean of 100 and a standard deviation of 25. consider a group of 400 people who take the test. how many people will score 90 or less? 63 138 180 262

Mean Score = u = 100
Standard Deviation = s = 25

First we need to find what is the probability that a student will score 90 or less than 90 in the test. So we need to convert 90 to the z score.



From z table we have to look for the -0.4. This values comes out to be 0.3446. This means the probability that z score is less than -0.4 is 0.3446. In terms of given data we can say that the probability the the scores of a students will be 90 or less is 0.3446.

This was probability for 1 student. For 400 students we simply multiply the probability with 400.

So, number of students who will score 90 or less = 400 x 0.3446 = 138

This means based on the data, 138 students will score 90 or less in the test.

So,option B gives the correct answer