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
jb00727 Forum Elite
Topics: 82 Posts: 190
01/01/04 - 11:09 PM
#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
mjl1717 Forum Hero
Topics: 958 Posts: 5,463
01/01/04 - 11:54 PM
#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
