Shelly Berman shelly@mathforum.org
If you toss a single number cube (one die), what is the probability of rolling an even number? One way of thinking about probability is to make a fraction that shows: (the number of things you want).
(the number of possibilities) - How many different numbers could you get when you roll a number cube?
- How many of these are even?
When you roll a number cube you can get any of the six numbers: 1, 2, 3, 4, 5, or 6. Three of these numbers are even: 2, 4, and 6. That is, the probability of rolling an even number can be written as: P(even number) = (3 numbers we want)/(6 possible numbers) = (3/6). So, the probability of rolling an even number on a number cube is (3/6). - Where is this on the probability scale from 0 to 1? How do you know?
How do you think we could measure the probability of tossing a die and getting a 1? - Is it more likely that you will get a 1 or that you won't get a 1?
- In fact, can you measure the probability of tossing a die and getting any number but a 1?
Experiment 3
Here's a set of twenty cards. Each card has a number from 1 to 10, and the number is either red or black. If I draw one card without looking, what is the probability that the card I draw will: |

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