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 assembly skill, which was described as "a task...

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 assembly skill, which was described as "a task requiring visual spatial skills related to mathematical competence.They 180 children born to cocaine users had a mean of 7.3 and a standard deviation of 2.9. The 182 children not exposed to cocaine had a mean score of 8.3 with a standard deviation of 3.1. Assume that the two samples are independent simple random sample selected from a normally distributed populations, and do not assume that the population standard deviation's are equal. Let's population 1 be hildren born to cocaine users.

use a 0.05 significance level to test the claim that prenatal cocaine exposure is associated with lower scores of four-year-old children on the test of object assembly.

What are the Null and alternative hypotheses. What is the test statistic?