A-Level Mathematics Question Analysis Topic: Mathematics - Probability
A bag X contains 4 white balls and 2 black balls, while another bag Y contains 3 white balls and 3 black balls. Two balls are drawn (without replacement) at random from one of the bags and were found to be one white and one black. Find the probability that the balls were drawn from bag Y.
Four white balls and two black balls are in bag X. Three white balls and three black balls are in bag Y.
There are 4 x 2 = 8 different methods to choose 1 white ball and 1 black ball from bag X.
3 x 3 = 9 different ways to choose one white ball and one black ball from bag Y.
8 + 9 adds out to 17.
The odds of drawing the balls from bag Y are 9/17.
End of analysis. Great!