Question

In a certain ASU classroom, the weight of men is an average of 175 pounds, with a standard deviation of 20 pounds. Assuming a normal distribution, approximately what percent of men in the class weigh between 135 and 215 pounds

Answer 1

99.8%

Explanation:

Normal Distribution

Standard deviation σ

mean equal to 175 pounds

We should remember approximately values for intervals:

[μ - σ/2 : μ + σ/2] values spread 1σ up and down mean equal to 68.3 %

[μ - σ : μ + σ ] values spread 2σ up and down mean equal to 95.7 %

and finally

[μ - 1.5 σ : μ + 1.5 σ ] values spread 3σ up and down mean equal to 99.7

In our case we were asked porcentage between 4σ (40 kg) spread about mean

175 + 40 = 215

175 - 40 = 135

For that interval we should get 99.8% of values