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 need explanation please  

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the IQ scores are obtained for a sample of 100 patients diagnosec with various types of schizophrenia who completed a standard IQ test battery. an additional 20 patients had to be dropped from the sample because they lacked the functional capacity to complete two or more portions of the test. four other patients refused to take test battery when offered the opportunity. results for the patients who completed the test battery gave an average IQ of 110 and a standard deviation of 20.
using this info compute 95% confidence interval for this estimate of the mean
a.70 to 130
b.70 to 150
c.85 to 115
d.90 to 130
e.105 to 115
f.106 to 114
i know its tough Q but i need to know it


The question is not easy for sure but I think it was well explained in Kaplan Q-bank... what part you did not get?


70 to 150


i only got the q, ill be grateful if you sent me the answer,plz


Memorize: Mean +/- Z (S / square root of N)
The mean is 110.
The standart deviation S is 20.
The sample size is 100.
Z is just a number to memorize, it is 1.96 or 2.0 for calculation. So, we use Z=2 to calculate 95%cofidence interval.

Put all numbers together: 110+/- 2(20/square root of 100) = 110+/- 4 = 106 to 114
F is correct

P.S. you are not suppose to pay attention to numbers of people who did not finish the test for this tpe of question.


thanks sigh you are so great


use these values in the formula of confidence interval.....

CI=mean+/-Z score(SD/sq. root of N)
Fis the correct answer....

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