A new cream that advertises that it can reduce wrinkles and improve skin was subject to a recent study. A sample of 48 women over the age of 50 used the new cream for 6 months. Of those 48 women, 42 of them reported skin improvement(as judged by a dermatologist). Is this evidence that the cream will improve the skin of more than 50% of women over the age of 50? Test using a=0.05. (a) Test statistic: z =_ (b) Critical Value: ======