MBA
Exam
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An urn contain 9 blue, 7 white and 4 black balls. If 2 balls are drawn at random, then what is the probability that only one ball is white ? 1) 71/190 2) 121/190 3) 91/190 4) 93/190 5) None of these
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- what is the answer...
- 11 years agoHelpfull: Yes(0) No(0)
- Method-I
No. of ways to succeed = 7*13 =91
No. of random pairs = 20C2 = 190
P(one white) = 91/190
Method-II
P(2 white) = 7C2/20C2 = 21/190
P(2 non-white) = 13C2/20C2
P(1 white) = 1-[(21+78)/20C2] = 1-99/190 = 91/190
- 9 years agoHelpfull: Yes(0) No(0)
- (7c1×13c1)÷20c2=91÷190
- 9 years agoHelpfull: Yes(0) No(0)
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