the weight of rats you wish to estimate the average weight of a pet rat. you obtain 40 rats (easily and cheaply done; keep them, because they make excellent pets), sampled uniformly at random and with replacement from the pet rat population. the mean weight is 340 grams, with a standard deviation of 75 grams. (a) give a 68% confidence interval for the weight of a pet rat, from this data. (b) give a 99% confidence interval for the weight of a pet rat, from this data.