Question

An experiment is broken up into two parts. In the first part of the experiment a penny is tossed in the air. If the coin lands on heads, then the coin is flipped a second time. If the coin lands on tails, then a six-sided die is rolled. What is the probability of getting exactly one tail?

Answer 1

There are two chances of getting one tails: if the first toss is heads and the second toss is tails OR if the first toss is tails.
The probability of the first toss to be head AND the second toss to be tails is 1/2 × 1/2, which equals 1/4.
The probability of getting a tails on the first toss is 1/2.

When dealing with probabilities, AND means multiply and OR means add. Therefore, this problem is: (heads AND tails) OR (tails). The probability of a coin landing on heads is 1/2 and the probability of a coin landing on tails is 1/2. Therefore, the equation is (1/2 × 1/2) + (1/2), which is 3/4.