There have been numerous studies involving the correlation and differences in IQ's among siblings. Here we consider a small example of such a study. We will test the claim that older siblings have a higher IQ than younger siblings. The results are depicted for a sample of 10 brothers in the table below.

	IQ score										mean	$s$
Older brother ($x$)	94	106	105	102	125	96	123	96	99	112	105.8	11.0332829807512
Younger brother ($y$)	94	105	104	102	125	93	119	93	99	106	104	10.760008261046
$d=x-y$	0	1	1	0	0	3	4	3	0	6	1.8	2.0976176963403

(a) Find the test statistic.

(b) Test the claim at the 0.01 significance level.

Critical value:

Is there sufficient data to support the claim?
Yes
No

(c) Test the claim at the 0.05 significance level.

Critical value:

Is there sufficient data to support the claim?
Yes
No