A study showed 118 instances of breast cancer among 3,303 mothers who used ...

     A study   showed 118 instances of breast cancer among 3,303 mothers who used   diethylstibestrol (DES), an estrogen-like substance formerly used to prevent   miscarriage, compared with 80 cases in 3,303 unexposed women comprising a   control group. At the 0.02 level of significance, was the incidence of cancer   greater in the DES users?