Video Transcript
A fair die is rolled 136 times. Calculate the expected number of times a number greater than three is rolled.
A fair die has six faces numbered from one to six. The probability of landing on each of these numbers is one-sixth. This means that the probability of landing on a number greater than three is three-sixths. We could land on four, five, or six. We can simplify this fraction to one-half by dividing the numerator and denominator by three. As we’re rolling the die 136 times, the expected number of times that we would expect a number greater than three is a half multiplied by 136.
Multiplying a number by a half or 0.5 is the same as dividing by two. We could calculate this using the bus stop method. Alternatively, 100 divided by two is 50, and 36 divided by two is 18. This means that 136 divided by two or one-half of 136 is 68. When rolling a fair die 136 times, we would expect to land on a number greater than three 68 times.
