Interpreting a bell curve questions

Question

The bell curve I am given is exactly the same as the one shown on the website listed below...

http://www.csus.edu/indiv/b/brocks/Courses/EDS%20245/Handouts/Week%2010/Descrptive%20Statistics%20and%20the%20Normal%20Curve.pdf

Questions

A.) About what percentage of the population falls within -1 and -2 standard deviations from the mean? I am not sure if the answer would be 47.7% (34.13 + 13.59) or just 13.59% because the wording of the question is confusing me.

B.) About what percentage of the population falls below -2 standard deviations from the mean? I think the answer is about 2.3% (.13 + 2.14) but I am not fully sure.

Any help is greatly appreciated, thank you for you time!

11/1/2013 | Leslie from Reno, NV | 1 Answer | 0 Votes

Answer 1

A.) The wording is slightly ambiguous. Most likely, they mean between -1 and -2 standard deviations from the mean, which is just 13.59%. If, however, they mean within -1 and within -2 standard deviations from the mean, the answer should be "34.13% and 47.7%, respectively." You should ask for clarification.

B.) You are correct.