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Let C 1 and C 2 be two biased coins such that the probabilities of getting head in a single toss are 2 3 and 1 3 , respectively. Suppose α is the number of heads that appear when C 1 is tossed twice, independently, and suppose β is the number of heads that appear when C 2 is tossed twice, independently. Then the probability that the roots of the quadratic polynomial x 2 – ax + β are real and equal, is-
- 40 81
- 20 81
- 1 2
- 1 4
Correct answer: 20 81
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