A rare form of malignant tumor occurs in 11 children in a? million, so its probability is 0.000011. Four cases of this tumor occurred in a certain? town, which had19 comma 635 children.
a. Assuming that this tumor occurs as? usual, find the mean number of cases in groups of 19 comma 635 children.
b. Using the unrounded mean from part ?(a?), find the probability that the number of tumor cases in a group of 19 comma 635 children is 0 or 1.
c. What is the probability of more than one? case?
d. Does the cluster of four cases appear to be attributable to random? chance? Why or why? not?