Probability 3 Question 5
5. An unbiased coin is tossed. If the outcome is a head, then a pair of unbiased dice is rolled and the sum of the numbers obtained on them is noted. If the toss of the coin results in tail, then a card from a well-shuffled pack of nine cards numbered is randomly picked and the number on the card is noted. The probability that the noted number is either 7 or 8 is
(a)
(b)
(c)
(d)
(2019 Main, 10 Jan I)
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Solution:
- Clearly,
Probability of getting head
Now, let
Then, $E _1={(6,1),(5,2),(4,3),(3,4),(2,5)$,
Also, let