(1) Organic chemists often purify organic compounds by a method known as fractional crys- tallization. An experimenter wanted to prepare and purify 4.85g of aniline. Ten 4.85g specimens of aniline were prepared and purified to produce acetanilide. The following dry yields were obtained: 3.85, 3.88, 3.90, 3.62, 3.72, 3.80, 3.85, 3.36, 4.01, 3.82. Assume the yields are a random sample from a normal distribution. (a) Construct a 95% lower confidence interval for the mean number of grams of acetanilide that can be recovered from 4.85g of aniline. (b) The experimenter believes that at least 4g of acetanilide can be recovered from 4.85g of aniline. Test at the 0.05 significance level whether his belief is true.