Edexcel S1 2011 June — Question 6

Exam BoardEdexcel
ModuleS1 (Statistics 1)
Year2011
SessionJune
TopicProbability Definitions
TypeBasic probability calculation

  1. Jake and Kamil are sometimes late for school.
The events \(J\) and \(K\) are defined as follows
\(J =\) the event that Jake is late for school
\(K =\) the event that Kamil is late for school
\(\mathrm { P } ( J ) = 0.25 , \mathrm { P } ( J \cap K ) = 0.15\) and \(\mathrm { P } \left( J ^ { \prime } \cap K ^ { \prime } \right) = 0.7\) On a randomly selected day, find the probability that
  1. at least one of Jake or Kamil are late for school,
  2. Kamil is late for school. Given that Jake is late for school,
  3. find the probability that Kamil is late. The teacher suspects that Jake being late for school and Kamil being late for school are linked in some way.
  4. Determine whether or not \(J\) and \(K\) are statistically independent.
  5. Comment on the teacher's suspicion in the light of your calculation in (d).