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Kaplan Qbank USMLE



Author5 Posts
  #1

A particular association determines mebership based on I.Q.Only those people with I.Q scpres atleast 2 standard deviations above mean on WAIS-R scale were eligible.Out of group of 400 people randomly selected,how many would be eligible for membership to the society?
a.2
b.4
c.6
d.8
e.10

NOTE; This is a Q from kaplan notes ,but the explanation given is I.q is scaled to have mean 100 and S.D. of 15. It says that 2.5% of people are above 2 S.D above mean.

Can anybody explain me plz?
Thanks

  #2

in a normal distribution,95% of the distribution falls within +/-2 standard deviations. Of the remaining 5%, 2.5% fall below -2 Standard deviation and 2.5% fall above 2 standard deviations. So tha ans will be 2.5% of 400=10

  #3

In addition
1) Draw a bell shaped curve, the mean is the average, in the midddle

2) Remember 68% of the distribution is +or- 1 standard deviation of mean

3)""""""""""""""9 5%"""""""""""""" 4;""""""""""+or - 2 standarddeviationsofmean

4)""""""""""""""9 9.7""""""""""""""&# 34;""""""""""+or- 3 standard deviations ofmean

Hope this helps

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  #4

Thx mjil

  #5

"mjl1717" wrote:

3)""""""""""""""9 5%"""""""""""""" 4;""""""""""+or - 2 standarddeviationsofmean






i think it is 95.5%

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