Question

A bag contains 18 balls out of which X are red. (1) if one balls is drawn at random from the bag what is the probability that it is not red. (2) if two more red balls are put in the bag the probability of drawing a red ball will be times the probability of drawing a red ball in the first case. Find the value of x

Answer 1

There are 18 balls among which some balls are red , so let red balls be 'x'. Then probablity of drawing red balls is x/18 and probality of not drawing red balls 18-x/18------- eq (1). Then according to second condition , x+2/20.then , x+2/20 = 18-×/18 by eqating we get,

18x+36=360_20x