CAIE S1 2011 June — Question 2

Exam BoardCAIE
ModuleS1 (Statistics 1)
Year2011
SessionJune
TopicApproximating Binomial to Normal Distribution
TypeJustify normal approximation

2 In Scotland, in November, on average \(80 \%\) of days are cloudy. Assume that the weather on any one day is independent of the weather on other days.
  1. Use a normal approximation to find the probability of there being fewer than 25 cloudy days in Scotland in November (30 days).
  2. Give a reason why the use of a normal approximation is justified.