Question

When Mrs. JHixson gave a test, the scores were normally distributed with a mean of 78 and a standard deviation of 6. This means that 95% of her students scored between which two scores?

A. 72 and 84


B. 66 and 90


C. 60 and 96


D. 60 and 100

Answer 1

For normal distribution 95% lie in the range mean-2*standard deviation for lower bound and mean+2*standard deviation for upper bound.

Upper bound is 78+2*6=78+12=90
Lower bound is 78-2*6=78-12=66
B. 66 and 90