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 Radha's present age = x years.∴ x = 2 (x = 12) - 3= x = 2x - 24 - 3= x = 27∴ Raja's present age = 4/9 x 27= 12 years ∴ Raja's age after 5 years = 12 + 5 = 17 years
EXAMIANS