Page 53 - UKCAT 2017

DM18
Father Christmas has a sack of wrapped presents from which visiting children can randomly select a gift. At the start, there are 15 presents of a harmonica and 15 of a drum in Father Christmas’s sack. By lunchtime, 5 harmonicas and 4 drums have been chosen.
Has the chance of a harmonica being randomly selected now increased when the next child collects a present?
DM19
Three students, Sarah, Simon and Paul test the same coin for bias.
The table gives information about their results.
Sarah and Simon pool their results to give their estimate of the probability that when the coin is thrown once it lands Heads. Paul uses his results to give his estimate.
Will Sarah and Simon’s estimate be better than Paul’s estimate?
A Yes, because it comes from two
different tests.
B Yes, because their separate estimates
are very close to each other.
C No, because Paul had more throws in
total.
D No, because Paul’s estimate will be
nearer one half.
Sarah
Simon
Paul
Throws
50
100
160
Heads
37
73
88
A
B
C
D
Yes, it was 1/2 and is now 10/21. Yes, it was 1/2 and is now 11/21. No, it was 1/2 and is now 11/21. No, it was 1/2 and is now 10/21.
UKCAT Of cial Guide 2017 53
PRACTICE QUESTIONS