Probability problems are often some of the most difficult questions on the exam. However, there's a great technique you can often use to make some of the toughest probability problems a lot easier. Try this example on for size. If I told you your probability of succeeding was (25 * 1.392)/100, how easy would that be to figure out? Now if I told if I told you your probability of failing was 55.5%, how easy would it be to figure out your probability of success?
The example above illustrates what often happens on the GMAT. The test-makers will ask you for the probability that something will happen. If you attempt to find the probability of it happening, it will take you forever. However, if you try to find out the probability that it won't happen, it's rather easy. Simply subtract the probability of failure from 1 and Voila! There's your probability of success.
Practice on the following example: If five coins are flipped simultaneously, what is the probability that at least two will be heads?
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