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Box 1 contains three cards bearing numbers 1, 2, 3 ; box 2 contains five cards bearing numbers 1, 2, 3, 4, 5 ; and box 3 contains seven cards bearing numbers 1, 2, 3, 4, 5, 6, 7. A card is drawn from each of the boxes. Let xi be the number on the card drawn from the ith box, i = 1, 2, 3.The probability that x1 , x2 , x3 are in an arithmetic progression, is(A) 9/105(B) 10/105(C) 11/105(D) 7/105 |
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Answer» (C) 11/105 Here 2x2 = x1 + x3 ⇒ x1 + x3 = even Hence number of favourable ways = 2C1 . 4C2 + 1C1 . 3C1 = 11. |
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