There are cutbacks at the Ripoff bank, which means that monstrous bonuses are no longer automatic. Instead they are now being allotted purely by chance to echo the aleatory nature of what passes for financial wisdom in the markets. In one game the chairman presents you with an urn into which a single ball has been placed without prejudice. That is, it is black or white with equal probability. All you have to do is withdraw a ball. If it is white you get an unjustifiable bonus, if black, you give it a miss that year.

“Come on, Carruthers,” says the chairman, seeing your reluctance, “golf awaits! Look, it’s easy. I’ll show you how it’s done.” And he bungs in an extra white ball, jiggles the urn and pulls out a ball at random: and Lo! It is white. Now it’s your go. What are the chances you get your bonus? What if, after his off-the-cuff demo, the chairman had absentmindedly replaced the white ball?

What would your chances have been then?

Each issue, we award a prize to three lucky winners – this time we have copies of Marcus Brigstocke's new book God Collar. You can send us your answers (complete with your postal address, if you want to win) to editor[at]newhumanist.org.uk. Deadline is 1 August 2011. We will publish the solution alongside next issue's quiz.

Solution to the May/June 2011 quiz, "A lurgical problem"

“It is easy to find out if you have two Grongebladders or two Gargols by counting the remaining pills in the bottles. You can’t have made a mistake earlier or you wouldn’t be alive. When you have done that, add to the three tablets already taken out one taken from that bottle which has more in it. We have transformed the problem into a slightly different one, which is easier to solve. Now you have two Grongebladders and two Gargols, though we don’t know which is which. Halve each tablet, putting one half on to one saucer and one on to the other. Now we have the correct dose on one saucer and the correct on the other. Consume the contents of one saucer on one day, and the contents of the other on the next. Panic over! Then carry on taking one of each per day from the bottles and be more careful in future: you don’t want to commit gulpable suicide.”