BMAT 2009 · Question 13 · Logic
SaveI have two bags of marbles. I know that at least one of the bags contains marbles of only one colour. I take one marble from the left hand bag, and put it into the right hand bag. I then take a marble from the right hand bag and put it into the left. I then tip the marbles out of the right hand bag and see that half the marbles are green and half of them red.
Which two of the following statements could not both be true? 1 The left hand bag started off with more than two marbles in. 2 The right hand bag started off with more than two marbles in. 3 The left hand bag started off with marbles of only one colour in. 4 The right hand bag started off with marbles of only one colour in.