Q22 of 29 Page 1

Suppose a girl throws a die. If she gets 1 or 2 she tosses a coin three times and notes the number of tails. If she gets 3,4,5or 6, she tosses a coin once and notes whether a ‘head’ or ‘tail’ is obtained. If she obtained exactly one ‘tail’, what is the probability that she threw 3,4,5 or 6 with the ride ?

Let A be the event that girl will get 1 or 2

P(A) = =


Let B be the event that girl will get 3, 4, 5 or 6


P(B) = =


P(T/A) = Probability of exactly one till given she will get 1 or 2 =


P(T/B) = Probability of exactly one till given she will get 3, 4, 5 or 6


=







Hence the probability that she threw 3,4,5 or 6 with the ride is .


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