SHEILY A.

asked • 07/27/14

which of the following values is not contained within 68% of the bell-shaped curve about the mean?

If the standard deviation of a set of values is 6.7 and the average value is 201.2.
Choices are ;
 
203.5

208.0

194.7

198.2

2 Answers By Expert Tutors

By:

SURENDRA K. answered • 07/27/14

Tutor
New to Wyzant

An experienced,patient & hardworking tutor

SURENDRA K.

Hello Dattaprabhakar,
 
Please confirm.
 
Surendra
Report

07/29/14

Dattaprabhakar G.

Hello Surendra:
 
What you rely on is a "rule of thumb" that 68 % of values lie within one SD.  If the question gives (a) the curve is "bell-shaped" (b) the population mean is 201.2 and (c) the population SD is 6.7, and you assume that the curve is actually a normal curve, you can go further.  You can compute the two limiting z_scores within which  0.68 of the area under the standard normal curve lies (as I have explained in my answer).
 
This opens up a philosophical question!  With the information given in (a), (b) and (c) above, to what extent you should (A) apply the rule of thumb or (B) assume normality and get more precise answers. 
 
Your call!!!
 
As a consultant, I would seek more information about the data plot, before answering the question.  The question, as it stands, is a typical, common,  and badly worded nightmare for students as well as for good statisticians.
 
Dattaprabhakar
 
 
Report

07/29/14

Dattaprabhakar G. answered • 07/27/14

Tutor
5 (2)

Expert Tutor for Stat and Math at all levels

Still looking for help? Get the right answer, fast.

Ask a question for free

Get a free answer to a quick problem.
Most questions answered within 4 hours.

OR

Find an Online Tutor Now

Choose an expert and meet online. No packages or subscriptions, pay only for the time you need.