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NNL
Awaitin The Unexpected  Topics: 779 Posts: 6613 |
A particular association determines membership on the basis of members IQ scores. Only those persons who have documented IQ scores at least 2 standard deviations above the mean on the Wechsler Adult Intelligence Scale (WAIS) are eligible for admission. Of a group of 200 people randomly selected from the population at large, how many would be eligible for membership to this society? A. 1 B. 2 C. 3 D. 4 E. 5
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yoga
| Forum Guru  Topics: 73 Posts: 637
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edie
| Forum Guru  Topics: 26 Posts: 1198
E
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po
| Forum Elite Topics: 39 Posts: 355
edie wrote: E  assuming Normal distribution= [got first aid help for this one] 1 SD=68% 2SD=95% 3SD=99.7% so, 95%out of 200 would mean 10[5 lower end and another 5 at the higher end]people scoring above and below 2SD=>they are asking for how many above 2SD would be eligible.
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hope4dabest
| Forum Guru  Topics: 23 Posts: 456
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hope4dabest
| Forum Guru Topics: 23 Posts: 456
OMG!! Never thought this way..thanks
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po
| Forum Elite Topics: 39 Posts: 355
dont worry I think we come under 95%,got wrong then learnt the right way
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hope4dabest
| Forum Guru Topics: 23 Posts: 456
po wrote: dont worry I think we come under 95%,got wrong then learnt the right way ...no worries i will be also happy with that
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edie
| Forum Guru Topics: 26 Posts: 1198
Yep, FA's got it, also check out biostats section of KLN Behavioral Science and know the distribution curve and SD correlations COLD 
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NNL
| Awaitin The Unexpected Topics: 779 Posts: 6613
edie wrote: E
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NNL
| Awaitin The Unexpected Topics: 779 Posts: 6613
The correct answer is E. 95% of a normally distributed population will fall between plus or minus 1.96 standard deviations from the mean. Since the population is normally distributed with regard to IQ, this means that approximately 2.5% of the population will have IQ scores 2 standard deviations or more above the mean, and 2.5% of the population will have IQ scores 2 standard deviations or more below the mean. 2.5% of 200 people is 5 people
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