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## PROBABILLITY

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**PROBABILLITY**Transition Math**What is Probability?**• Probability is a number from 0 to 1 that tells you how likely something is to happen. • Probability can be either theoretical or experimental.**THEORETICAL**Theoretical probability can be found without doing and experiment. EXPERIMENTAL Experimental probability is found by repeating an experiment and observing the outcomes. Probability**HEADS**TAILS THEORETICAL PROBABILITY • I have a quarterMy quarter has a heads side and a tails side • Since my quarter has only 2 sides, there are only 2 possible outcomes when I flip it. It will either land on heads, or tails**HEADS**TAILS THEORETICAL PROBABILITY • When I flip my coin, the probability that my coin will land on heads is 1 in 2 • What is the probability that my coin will land on tails??**HEADS**TAILS Theoretical Probability Right!!! There is a 1 in 2 probability that my coin will land on tails!!! • A probability of 1 in 2 can be written in three ways: • As a fraction: ½ • As a decimal: .50 • As a percent: 50%**A**A A A Theoretical probability When I spin this spinner, I have a 1 in 4 chance of landing on the section with the red A in it.**A**A A A Theoretical Probability A 1 in 4 chance can be written 3 ways: • As a fraction: ¼ • As a decimal: .25 • As a percent: 25%**Theoretical Probability**I have three marbles in a bag. • I am going to take 1 marble from the bag. • What is the probability that I will pick out a red marble? 1 marble is red 1 marble is blue 1 marble is green**Theoretical Probability**• Since there are three marbles and only one is red, I have a 1 in 3 chance of picking out a red marble. • I can write this in three ways: • As a fraction: 1/3 • As a decimal: .33 • As a percent: 33%**Experimental Probability**Experimental probability is found by repeating an experiment and observing the outcomes.**Experimental Probability**• Remember the bag of marbles? • The bag has only 1 red, 1 green, and 1 blue marble in it. • There are a total of 3 marbles in the bag. • Theoretical Probability says there is a 1 in 3 chance of selecting a red, a green or a blue marble.**Experimental Probability**• Draw 1 marble from the bag. • It is a red marble. • Record the outcome on the tally sheet**Experimental Probability**• Put the red marble back in the bag and draw again. • This time your drew a green marble. • Record this outcome on the tally sheet.**Experimental Probability**• Place the green marble back in the bag. • Continue drawing marbles and recording outcomes until you have drawn 6 times. (remember to place each marble back in the bag before drawing again.)**Experimental Probability**• After 6 draws your chart will look similar to this. • Look at the red column. • Of our 6 draws, we selected a red marble 2 times.**Experimental Probability**• The experimental probability of drawing a red marble was 2 in 6. • This can be expressed as a fraction: 2/6 or 1/3 a decimal : .33 or a percentage: 33%**Experimental Probability**• Notice the Experimental Probability of drawing a red, blue or green marble.**Comparing Experimental and Theoretical Probability**• Look at the chart at the right. • Is the experimental probability always the same as the theoretical probability?**Comparing Experimental and Theoretical Probability**• In this experiment, the experimental and theoretical probabilities of selecting a red marble are equal.**Comparing Experimental and Theoretical Probability**• The experimental probability of selecting a blue marble is less than the theoretical probability. • The experimental probability of selecting a green marble is greater than the theoretical probability.**Probability Review**Probability is a number from 0 to 1 that tells you how likely something is to happen. • Theoretical (can be found without doing an experiment) • Experimental (can be found by repeating an experiment and recording outcomes.) There are 2 types of probability:**Probability Review**• Probability can be expressed as a fraction, a decimal or a percentage.