The length of students' college careers at Anytown University is known to be normally distributed, with a mean length of 5.5 years and a standard deviation of 1.75 years. What percent of students have college careers lasting between 2 and 9 years?
A) 50%
B) 99.75%
C) 68%
D) 95%

Question

Quizplus · Accepted Answer

We need to find the percentage of students whose college careers lasted between 2 and 9 years. Using the z-score formula, we can find the z-scores for both 2 and 9 years:
z-score for 2 years: (2-5.5)/1.75 = -2
z-score for 9 years: (9-5.5)/1.75 = 2
From the z-tables, we can find that the area under the standard normal distribution curve between -2 and 2 is approximately 0.95, or 95%. Therefore, approximately 95% of students have college careers lasting between 2 and 9 years. The correct choice is D.

The Length of Students' College Careers at Anytown University Is