Based on the Normal model for car speeds (in km/h) on a road N(77,9.1) ,what are the cutoff values for the middle 20% of the speeds?

A) about 84.7 km/h,about 69.3 km/h
B) about 86.1 km/h,about 67.9 km/h
C) about 61.6 km/h,about 92.4 km/h
D) about 95.2 km/h,about 58.8 km/h
E) about 74.7 km/h,about 79.3 km/h

The middle 20% of speeds would be centered around the mean (77 km/h) of the normal distribution. Choices A, B, C, and D all have cutoff values that are not symmetrically distributed around the mean. Choice E, with cutoff values of about 74.7 km/h and about 79.3 km/h, is the only one that is symmetrically distributed around the mean, fitting the characteristic of a normal distribution for the middle 20%.