2. Probability What are your Chances?

3. Overview Probability is the study of random events. The probability, or chance, that an event will happen can be described by a number between 0 and 1: A probability of 0, or 0%, means the event has no chance of happening. A probability of 1/2, or 50%, means the event is just as likely to happen as not to happen. A probability of 1, or 100%, means the event is certain to happen. For instance, the probability of a coin landing heads up is ½, or 50%, This means you would expect a coin to land “heads up” half of the time.

4. Overview The language of probability includes: Experiment – a systematic investigation where the answer is unknown You can represent the probability of an event by marking it on a number line like this one Impossible 0 = 0% Certain 1 = 100% 50 – 50 Chance ½,.5, 50% number of possible outcomes Probability = number of favorable outcomes

5. Ways to write Probability Fractions Percent Or Decimal Most Common Way: Fraction or Percent

6. 1. What is the probability that the spinner will stop on part A? 2.What is the probability that the spinner will stop on (a)An even number? (b)An odd number? 3. What fraction names the probability that the spinner will stop in the area marked A? AB CD 3 1 2 A CB

7. Probability Questions Lawrence is the captain of his track team. The team is deciding on a color and all eight members wrote their choice down on equal size cards. If Lawrence picks one card at random, what is the probability that he will pick blue? yellow red blue green black

8. Coin Toss Record your data on the handout that looks like this. Toss a coin 25 times. Total the number of heads and tails. What percent was heads? Tails? Toss a coin another 25 times. Total the number of heads and tails for this trial. Add both trials together. Is there a difference in the percentage when you calculate 50 tosses versus 25 tosses?

9. Squares in a Bag 1.Before doing the experiment. First, calculate the probability of choosing each color on your handout. 2.Then without looking, pick a square out of the cup 25 times. 3.Record your scores. 4.Calculate the experimental probability. 5.Compare the two amounts There are 5 yellow, 3 blue, and 2 red squares in the cup.

10. Activity Part 1 Using 1 die with the numbers 1-6. Conduct a trial by rolling the die 100 times (25 each). What do you think is the probability of picking a 1. How many times did you roll 1, 2, 3, 4, 5, 6? What is the percentage for each number? Part 2 Combine your 100 rolls with the 3 other people. What is the percentage for each number out of the now 400 rolls/picks?