Unit 6 Lesson 2 Probabilities and Predictions

Essential Question:

How are theoretical probabilities used to make predictions or decisions? 

Probabilities and Predictions

You can conduct an experiment to help determine the probability of an event.

Theo spun a quarter on his desk and observed whether it landed heads up or tails up. He did this 50 times and recorded his results in the table.

1. Determine the experimental probability of the coin landing heads up?– P(heads up) = 24/50 = 12/25

2. Determine the experimental probability of the coin landing tails up?– P(tails up) = 26/50 = 13/50

Spinning a

QuarterNumber of Times

Heads

24

Tails

26

Total Trials

50

Remember P(event) =

favorable outcomes /

total possible outcomes

Example 1

Predict the number of times you would predict the quarter to land heads up and tails up if you performed this experiment 80 times.

Example 2

The table shows the results of spinning a spinner 10 times. If you spin this spinner 40 times, predict how many times the spinner will land on a yellow section.

Number of times

Blue 2

Orange 5

Yellow 3

Total 10

Example 3

• This spinner is divided into six congruent sections. 1. Spin the spinner 18 times.2. Tally each time a number is

spun.3. Total the tally marks.

• My experimental probability of spinning a 5 was __________.

• If I could spin the spinner 80 times, I predict the spinner would land on the number 5 ________ times.

Number

Tallies

Times Spun

123456

Show What You’ve Learned

• Cynthia drew a tile from a bag, recorded its color, and replaced it in the bag. The table shows her results.– If there are a total

of 35 tiles in the bag, predict how many are silver.

Drawing Tiles

Number of Tiles

Black 24Silver 36Total Trials

60

Assignments

Classwork Gigi the Dancer worksheet

Please hold on to this until tomorrow.

Homework none

REMINDER: Classwork not completed in class should be completed as homework.