A sample of n 5 10 automobiles was selected, and each was subjected to a 5-mph crash test. Denoting a car with no visible damage by S (for success) and a car with such damage by F, results were as follows:
S S F S S S F F S S
a. What is the value of the sample proportion of successes x/n?
b. Replace each S with a 1 and each F with a 0. Then calculate  for this numerically coded sample. How does  compare to x/n?
c. Suppose it is decided to include 15 more cars in the experiment. How many of these would have to be S's to give x/n = .80 for the entire sample of 25 cars?