There are 30 balls in the bag, 10 of which are blue. Adam takes 2 balls out of the bag without a replacement and calculated that there is a probability of 0.2 of both balls being blue. What percentage error did he make compared to the true probability?
True probability of 2 consecutive balls picked being blue: (10/30)*(9/29)=3/29 which is 0.1034 (4 d.p.)
3/29-100% 0.2-x% so, x=0.2*100/(3/29)= 193.3 (1 d.p.) therefore Adam's result is 93.3 % (1 d.p.) over the true result
DK
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