Birth Weights of Male Babies| Confidence Interval and Hypothesis Testing for Population Mean and Standard Deviation| Statistics

Birth weights of male babies at one hospital were recorded for 200 births of boys. A mean of that sample was  35.3 hg and a standard deviation of 7.2 hg.  a) Construct a 90% confidence interval for the mean of all boy baby weights. b) A medical Journal claims that the mean weight of male babies is 37.0 hg. Test that claim at a 0.10 level of significance.  c) Use a 0.05 level of significance to test a claim that the real standard deviation of boy birth weights is 6.75 hg.