In a test of the MicroSort method of gender selection, 302 babies are born to couples trying to have baby girls, and 187 of those babies are girls.

If the gender-selection method has no effect and boys and girls are equally likely, find the mean and standard deviation for the numbers of girls born in groups of 302.
$\displaystyle \mu=$ girls (Round answer to one decimal place.) 
$\displaystyle \sigma=$ girls (Round answer to two decimal places.) 

Give the interval of usual values for the number of girls born in groups of 302, using the range rule.
Usual number of girls = Enter answer as an interval with whole numbers endpoints (and square-brackets).
Does it appear that the gender-selection method is effective in providing couples with girls?