OCR MEI S1 2010 January — Question 4

Exam BoardOCR MEI
ModuleS1 (Statistics 1)
Year2010
SessionJanuary
TopicBinomial Distribution
TypeSingle batch expected count

4 In a multiple-choice test there are 30 questions. For each question, there is a \(60 \%\) chance that a randomly selected student answers correctly, independently of all other questions.
  1. Find the probability that a randomly selected student gets a total of exactly 20 questions correct.
  2. If 100 randomly selected students take the test, find the expected number of students who get exactly 20 questions correct.