Question

The distribution of the amount of money spent by students on textbooks in a semester is approximately normal in shape with a mean of 434 and a standard deviation of 31. According to the standard deviation rule, approximately 99.7% of the students spent between ____$ and ______$ on textbooks in a semester.

Answer 1

Hence, approximately 99.7% of students spend between : $341 and $527

Explanation:

According to the empirical rule :

99.7% fall within 3 standard deviations from the mean

Given that :

Mean, μ = 434

Standard deviation, σ = 31

μ ± 3σ

μ - 3σ = 434 - 3(31) = 434 - 93 = 341

μ + 3σ = 434 + 3(31) = 434 + 93 = 527

Hence, approximately 99.7% of students spend between : $341 and $527 on textbooks in a semester.