8.3 Making Predictions Lesson

Unit 8 Day 3
Making Predications with Probability

• You can use the theoretical probability of an event happening to predict the number of times the event will occur in the future by creating a proportional relationship.

• Making these predictions is always an estimate. The actual results may (and probability will) be different, but using the proportion gives us a general idea of what to expect. Sometimes we get a decimal answer and we have to round.

• Generally speaking, the more times you perform the event, the closer the results will be to the prediction.

IT'S PROPORTIONAL

Example

Match

Match each proportion to the question that it would answer.

• I choose a card out of a standard deck of playing cards, look at it, and replace it each time. About how many times could I expect to get a 4 if I repeat this process 350 times?

• I flip a coin 30 times. About how many times could I expect to it to land on tails?

• There is a spinner will four equal sections labeled 1, 2, 3, 4. If I spin 350 times, about how many times could I expect it to land on the 3?

• I roll a standard number cube 30 times. About how many times could I expect the cube to land on a number less than 3?

• $$\frac{4}{52}=\frac{x}{350}$$

• $$\frac{1}{2}=\frac{x}{30}$$

• $$\frac{1}{4}=\frac{x}{350}$$

• $$\frac{2}{6}=\frac{x}{30}$$

• You can also use previous or given data to predict the number of times the event will occur in the future by creating a proportional relationship.

• Remember, making these predictions is always an estimate. The actual results may (and probability will) be different, but using the proportion gives us a general idea of what to expect. Sometimes we get a decimal answer and we have to round. (You can't roll ½ of a 6.)

IT'S PROPORTIONAL

Example

Multiple Choice

Gavin is on the bowling team. He knows that in the past week, he has bowled a strike 8 times in the past 5 games. How many more strikes should Gavin expect to bowl if he plays 15 more games?

• about 24 more strikes

• exactly 24 more strikes

• about 9 more strikes

• exactly 8 more strikes