3) Normal baby birth weights have a mean of 3103 grams. Prenatal cocaine use is believed to cause birth weights to be below the normal birth weights. A sample of 19 infants born form parents that used cocaine yielded a mean weight of 2700 grams with a standard deviation of 645 grams. Use a significance level of 0.025 to test the claim.

4) Major league baseballs should have a bounce height of 92.84 inches when dropped form 24 feet. I retired major league batter claims that reason more home runs are being recorded is because new major league baseballs have a bounce height greater than the required height. A sample of 28 newly produced major league baseball's yields a mean bounce height of 93.65 inches with a standard deviation of 1.76 inches. Use .01 to test the retired major league batter claim.