According to a recent study by the National Highway Traffic Safety Administration (NHTSA), the helmet usage rate for motorcyclists in the US was 55%. If this is the case and you select 15 cyclists at random, how likely is it that
a. Exactly 12 of them will be helmet users?
b. No more than nine of them will be helmet users?
c. Between nine and 11 of them will not be helmet users?
d. What is the expected number of motorcyclists in this group of 15 who are not helmet users?

  • CreatedJuly 16, 2015
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