Number System
A bag contains four red, six black and seven green balls. Three balls are drawn randomly. What is the probability that the balls drawn contain exactly two red balls ?
Total balls = 4 + 6 + 7 = 17∴ n(S) = 17C1 = 680Two red balls can be selected from four red balls in 4C2 = 6 ways.and the third ball can be selected from the remaining 13 balls in 13C1 = 13 ways.∴ P (E) = 13x6/680 = 39/340
Let the consecutive odd number be x, x + 2, x + 4 and x + 6 respectively.According to the question x + x + 2 + x + 4 + x + 6 = 104 = 4x + 12 = 104 = 4x = 104 - 12 = 92∴ x = 92/4 = 23∴ Required number = x + 4= 23 + 4 = 27
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