Cell Phone and Brain Cancer. In a study of 420,095 cell user in Denmark, it was found that 135 developed cancer of the brain or nervous system. If we assume that the use of cell phones has no effect on developing such cancer, then the probability of a person having such a cancer is 0.000340.
a) Assuming that cell phones have no effect on developing cancer, find the mean and standard deviation for the number of people in groups of 420,095 that can be expected to have cancer of the brain or nervous system.
b) Based on the results from part (a), it is unusual to find that among 420,095 people, there are 135 cases of cancer of the brain or nervous system? Why or why not?
c) What do these results suggests about the publicized concern that cell phones are a health danger because they increase the risk of cancer of the brain or nervous system?