Question

In the recent history of an introductory econometrics course, the final grades of students have a mean of 75, a standard deviation of 6 and are approximately normally distributed. In which of the following intervals do you expect 95% of final grades to lie in?

None of the other answers is correct.

In the interval (60,90).

In the interval (69,81).

In the interval (63,87).

Answer 1

Answer:

In the interval (63,87).

Explanation:

Mean () = 75

Standard deviation() = 6

For normal distribution approximately about 95% of the values fall within two standard deviations from the mean.

In this case, 2* = 2*6 = 12.

Therefore, the range within which 95% values lie = ( - 2, +2) = (75-12, 75+12) = (63, 87)