Video: Finding the Probability of Rolling an Odd Number on a Fair Die

What is the probability of rolling an odd number on a fair die?

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Video Transcript

What is the probability of rolling an odd number on a fair die?

A fair die has six faces numbered one, two, three, four, five, and six. We were asked to work out the probability of rolling an odd number. A number is odd if it is not divisible exactly by two. In this case, the numbers one, three, and five are odd, whereas two, four, and six are even as they are divisible by two.

The probability of an event occurring can be written as a fraction where the numerator is the number of successful outcomes, what we want to happen, and the denominator is the number of possible outcomes, everything that can happen. In this case, there are three odd numbers. Therefore, our numerator is three. The denominator is six as there are six numbers on the dice. There are six possible outcomes.

The fraction three sixths can be simplified as the numerator and denominator are both divisible by three. Remember, whatever you do to the top, you must do the bottom. Dividing the numerator by three gives us one as three divided by three is equal to one. And dividing the denominator by three give us an answer two. Six divided by three equals two.

This means that the probability of rolling an odd number on a fair dice is one-half. This could also be written as a decimal as 0.5 or a percentage as 50 percent.

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