Two balls can be drawn from 18 balls in 18C2 Ways, ie 153 ways. One white from 8 white balls can be drawn in 8C1 = 8 ways and one black ball from 10 black can be drawn in 10C1 = 10 ways.∴ n(S) = 153, n(E) = 8 x 10 = 80∴ P(E) = 80/153
In 150 litre, milk is 84%ie 150 x 84/100 = 126 litre Let us add x litres of waterTherefore, the quantity of mixture = 150 + x∴ 52.5% of (150 + x) = 126 litres 150 + x = 126x100/52.5 = 240 litres∴ x = 240 - 150 = 90 litres