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Predicting with Probability

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1. The school is having a fund-raising draw. First prize is meal for four at a local restaurant. There are 200 tickets sold. Sol buys 4 tickets. What is the probability of him winning the first prize?

Probability = 4/200 = 0.02

2. If you rolled a dice 24 times, how many times would you expect to roll a six?

Probability of a six = 1/6

Probability x number of rolls = 1/6 x 24 = 4

A six would be expected 4 times.

3. If you rolled a dice 48 times, how many times would you predict not to roll a six?

Probability of a six = 1/6. Probability of not rolling a six = 1 - 1/6 = 5/6

Probability x number of rolls = 5/6 x 48 = 40

A six would not be expected on 40 rolls of the dice.

4. If you rolled a dice 96 times, how many times would you expect to roll a three or a six?

Probability of a three or a six = 2/6

Probability x number of rolls = 2/6 x 96 = 32

A three or a six would be expected 32 times.

5. The local weather forecaster says she can predict whether it will rain with 80% accuracy which is equivalent to a 0.8 chance of being correct. If she forecasts rain 160 times, how many of these times would you expect she is wrong?

Probability of being wrong = 1 - Probability of being correct = 1 - 0.8 = 0.2

Probability x number of forecasts = 0.2 x 160 = 32

It would be expected that she is wrong 32 times.

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A Probability Worksheet    -    By HelpingWithMath.com

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Similar to the above listing, the resources below are aligned to related standards in the Common Core For Mathematics that together support the following learning outcome:

Investigate chance processes and develop, use, and evaluate probability models

 

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