Scores on a test are normally distributed with a mean of 76 and a standard deviation of 6. Using the z-score table, estimate the probability a randomly selected student scored below a 64.

Question

Select one: a. 1.2 b. 0.02 c. -0.02 d. 0.98

Answer 1

First, compute the z-score:

z = (x-μ)/σ

1. z = the z-score
2. x = the data point = 64
3. μ = the mean = 76
4. σ = the standard deviation = 6

Plug the numbers into the z-score formula and compute the z-score. Then look the z-score up in a z-score table and read off the value. That value is the probability that a random student scored below a 64.