CAIE S1 2007 November — Question 6

Exam BoardCAIE
ModuleS1 (Statistics 1)
Year2007
SessionNovember
TopicBinomial Distribution
TypeDirect binomial probability calculation

6 On any occasion when a particular gymnast performs a certain routine, the probability that she will perform it correctly is 0.65 , independently of all other occasions.
  1. Find the probability that she will perform the routine correctly on exactly 5 occasions out 7 .
  2. On one day she performs the routine 50 times. Use a suitable approximation to estimate the probability that she will perform the routine correctly on fewer than 29 occasions.
  3. On another day she performs the routine \(n\) times. Find the smallest value of \(n\) for which the expected number of correct performances is at least 8 .