1. The probability you will have at least one head on three coin flips is equal to 1 minus the probability that you have no heads on three flips. The probability you will have 0 heads on three flips is . Then the probability of at least one head is . An alternative way is to simply list all possible outcomes and count them or to add the probability of exactly one head ( , exactly two heads , and exactly three heads .

2. There are 2 composite numbers on a single dice (4 and 6). Thus, you have a chance of rolling a composite number.