A study was conducted to assess the effects that occur when children are exposed to cocaine before birth. Children were tested at age 4 for object assemblyskill, which was described as"a task requiringvisual-spatial skills related to mathematicalcompetence." The 193 children born to cocaine users had a mean of 7.4 and a standard deviation of 3.0. The 189 children not exposed to cocaine had a mean score of 8.2 with a standard deviation of 2.9. Assume that the two samples are independent simple random samples selected from normally distributedpopulations, and do not assume that the population standard deviations are equal. Let population 1 be children born to cocaine users. Complete parts(a) and(b) below.

a. Use a 0.10 significance level to test the claim that prenatal cocaine exposure is associated with lower scores offour-year-old children on the test of object assembly.

Identify the null and alternative hypotheses.

A.

H0: 1>2

H1: 1=2

B.

H0: 1<2

H1: 1=2

C.

H0: 12

H1: 1=2

D.

H0: 1=2

H1: 12

E.

H0: 1=2

H1: 1>2

F.

H0: 1=2

H1: 1<2

The test statistic is

negative 2.65

TheP-value is

0.004

State the conclusion for the test. Reject the null hypothesis. There is sufficient evidence to support the claim that prenatal cocaine exposure is associated with lower scores offour-year-old children on the test of object assembly

b. Test the claim in part(a) by using a confidence interval.

The ? % confidence interval estimate is ? <12< ?

(Round to one decimal place asneeded.)