SAT Video Tip Probability Challenge Question

The magic formula to remember for probability questions is the following: (# of desired outcomes)/(# of possible outcomes) For instance, if a question asks what is the probability of rolling an even number on a six-sided die, you would count the number of desired outcomes, which in this case is even numbers: 2, 4, and 6. That is a total of 3 possibilities, so that number goes in the numerator. The number of possible outcomes is 6, since there are six different numbers (1-6) you can get when tossing a six-sided die. Our equation will look like this: 3/6 =  ½ Many of you probably knew that already. You want the tough stuff—after all this is a challenge question. Before I throw you a toughie, one quick note: getting the hard questions right on the SAT is about being able to think â€Å"on the fly†. You can’t just plug the information into some handy formula and out will come the answer. The formula above will only be of use once you’ve â€Å"cracked† the problem and figured out which number goes in the numerator and which one in the denominator. Good luck! What is the probability of rolling three six-sided fair dice so that exactly one of the three numbers rolled is prime? (A)   1/72 (B)   1/27 (C)   1/3 (D) 1/8 (E)   3/8 The answer and explanation are in the video below. Enjoy! 🙂