AQA S1 2013 January — Question 5

Exam BoardAQA
ModuleS1 (Statistics 1)
Year2013
SessionJanuary
TopicConditional Probability
TypeBasic two-way table probability

5 Roger is an active retired lecturer. Each day after breakfast, he decides whether the weather for that day is going to be fine ( \(F\) ), dull ( \(D\) ) or wet ( \(W\) ). He then decides on only one of four activities for the day: cycling ( \(C\) ), gardening ( \(G\) ), shopping ( \(S\) ) or relaxing \(( R )\). His decisions from day to day may be assumed to be independent. The table shows Roger's probabilities for each combination of weather and activity.
\multirow{2}{*}{}Weather
Fine ( \(F\) )Dull ( \(D\) )Wet ( \(\boldsymbol { W }\) )
\multirow{4}{*}{Activity}Cycling ( \(\boldsymbol { C }\) )0.300.100
Gardening ( \(\boldsymbol { G }\) )0.250.050
Shopping ( \(\boldsymbol { S }\) )00.100.05
Relaxing ( \(\boldsymbol { R }\) )00.050.10
  1. Find the probability that, on a particular day, Roger decided:
    1. that it was going to be fine and that he would go cycling;
    2. on either gardening or shopping;
    3. to go cycling, given that he had decided that it was going to be fine;
    4. not to relax, given that he had decided that it was going to be dull;
    5. that it was going to be fine, given that he did not go cycling.
  2. Calculate the probability that, on a particular Saturday and Sunday, Roger decided that it was going to be fine and decided on the same activity for both days.