Question

Suppose that grade point averages of undergraduate students at one university have a bell-shaped distribution with a mean of 2.62 and a standard deviation of 0.4. Using the empirical rule, what percentage of the students have grade point averages that are no more than 1.82? Please do not round your answer.

Answer 1

The percentage of the students who have grade point averages that are no more than 1.82 is 2.5%

Explanation:

The empirical rule states that for a normal distribution, 68% of the distribution are within one standard deviation from the mean, 95% are within two standard deviations from the mean and 99.7% are within three standard deviations from the mean.

Given that:

Mean (μ) = 2.62, Standard deviation (σ) = 0.4

68% are within one standard deviation = μ ± σ = 2.62 ± 0.4 = (2.22, 3.02)

95% are within two standard deviations = μ ± 2σ = 2.62 ± 2(0.4) = (1.82, 3.42)

The percentage of the students have grade point averages that are no more than 1.82 is 100% - [95% + (100% - 95%)/2] = 100% - 97.5% = 2.5%