Assume that different groups of couples use a particular method of gender selection and each couple gives birth to one baby. this method is designed to increase the likelihood that each baby will be a girl, but assume that the method has no effect, so the probability of a girl is 0.5. assume that the groups consist of 19 couples. a. find the mean and the standard deviation for the numbers of girls in groups of 19 births. b. use the range rule of thumb to find the values separating results that are significantly low or significantly high.