This GMAT Math practice question is a Permutation and Combination problem solving question and the concept tested is finding the outcomes when a set of coins are tossed simultaneously.
- 3 * 28
- 3 * 29
- None of these
When a coin is tossed once, there are two outcomes. It can turn up a head or a tail.
When 10 coins are tossed simultaneously, the total number of outcomes = 210
Out of these, if the third coin has to turn up a head, then the number of possibilities for the third coin is only 1 as the outcome is fixed as head.
We need to find out what happens to the remaining 9 coins?
The remaining 9 coins can turn up either a head or a tail. Each of the 9 coins has 2 possibilities.
Number of outcomes for the remaining 9 coins = 29
∴ the number of outcomes in which the 3rd coin turns a head = 1 * 29 = 29.
Choice D is the correct answer.