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	85	104	129	112	88	93	116	79	96	104
Test B	85	104	130	117	88	96	119	78	95	104

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. Assume differences are normal. (Note: You may wish to use software.)

(a) The test statistic is (at least 2 digits after the decimal)

(b) The critical value is (at least 3 digits after the decimal)

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

A. No
B. Yes


(d) Construct a 99% confidence interval for the mean of the differences. Again, use (Test A - Test B) Use 3 digits after the decimal.

Answer 1

a)

test statistic is =-1.58

b)

critical value is =-2.821

c)

A) NO (since test statistic is not less than critical value)

d)

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=		2.055
lower confidence limit                     =		-3.055
upper confidence limit                    =		1.055
from above 99% confidence interval for population mean =(-3.055,1.055)