SURENDRA K. answered • 07/27/14

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Lower limit should be 201.2-6.7*1=194.5

Upper limit should be 201.2+6.7*1=207.9

There is a thumb rule also that 68% of values lie within one standard deviation.

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

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07/29/14

SURENDRA K.

07/29/14