Question

Ten randomly selected people took an IQ test A, and next day they took a very similar IQ test B. Their scores are shown in the table below.

Person	A	B	C	D	E	F	G	H	I	J
Test A	115	105	80	90	125	81	104	99	108	94
Test B	115	103	80	91	124	81	107	99	106	92

1. Consider (Test A - Test B). Use a 0.01 significance level to test the claim that people do better on the second test than they do on the first. (Note: You may wish to use software.)

(a) What test method should be used?

A. Two Sample z
B. Two Sample t
C. Matched Pairs

(b) The test statistic is

(c) The critical value is

(d) Is there sufficient evidence to support the claim that people do better on the second test?

A. Yes
B. No


2. Construct a 99% confidence interval for the mean of the differences. Again, use (Test A - Test B).
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Answer 1

a) C. Matched Pairs

b)test statistic =0.605 ( please try 0.604 if this comes wrong)

(c) The critical value is= -2.821

d)

No

2)

for 99% CI; and 9 degree of freedom, value of t=			3.250
therefore confidence interval=		sample mean -/+ t*std error
margin of errror          =t*std error=		1.610
lower confidence limit                     =		-1.310
upper confidence limit                    =		1.910

99%   confidence interval for the mean of the differences =-1.310 ; 1.910

( please try -1.314 ; 1.914 if abve comes wrong and revert)