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7-49.

Lue is rolling a random number cube. The cube has six sides, and each one is labeled with a different number through .  

  1. What is the probability that he will roll a or a on one roll?

    Each number has an equal probability of being rolled. Since there are total sides, what is the probability of getting any number?

    Each number has a one-in-six probability of being rolled. Since we can roll either a or a , we can add the probabilities of these two numbers together.

  2. What is the probability that he will roll a and then a in two rolls?

    There is a one-in-six probability of Lue rolling a in the first roll, and there is a one-in-six probability of him rolling a in the following roll. Since the order of the numbers rolled must be taken into account, we must multiply these two numbers together.

  3. What is the probability that he will roll a sum of in two rolls?

    See part (b).