Presentation on theme: "Probability & The Fundamental Counting Principle Lesson 23."— Presentation transcript:
Probability & The Fundamental Counting Principle Lesson 23
The six faces of a die have dots on them corresponding to the numbers 1 trough 6. 1 dot shows on the top of the die above. If a die is tossed many times, the 1-dot face should appear on top about 1 out of 6 times, or 1/6 if the time.
Read through the following lesson. Answer the Try This questions. Show your work!
We say that the probability of rolling a 1 in one toss is 1/6. In the ratio 1/6, 1 is the number of successful outcomes: s 6 is the total number of possible outcomes: t.
This suggests the following formula for the probability of an event: P(E) = = s t Number of successful outcomes Total number of outcomes
Example One: This is a dart board with both shaded and unshaded squares. If you throw a dart without looking and it lands on the board, what is the probability that it landed on a shaded square? A. 2/5 B. ½ C. 3/5 D. 2/3
Strategy: There is a total of 20 possible squares or outcomes. 8 squares are shaded: 8 favorable or successful outcomes. There are 8 favorable outcomes out of 20 possible outcomes. The chances or probability that the dart will land on a shaded square if therefore 8 out of 20 or 8/20. 8 number of successful outcomes 20 total number of possible outcomes SOLUTION: the probability is 8/20 = 2/5 choice A
Try This # 1 If the spinner below is spun, what is the possibility that the arrow will land on an S? A. 5/8B. 3/8 C. 3/5D. ½ S S S T P R P T
Example 2: The points scored by Middletown Intermediate School are recorded below. What is the probability that the team scored fewer than 54 points in one game chosen random?
Strategy: There is a total of 15 possible outcomes: 35, 28, 40, 44, 41, scores less than 53 SO the probability of scoring less than 54 is : number of successful outcomes 6 total number of outcomes 15 6/15 = 2/5
Try This # 2 Use the table of scores in Example 2 to answer the following question. What is the probability that the team scored greater than 60 points in one game chosen at random?
Try This # 3 If a computer randomly chooses a letter in the word algebra, what is the probability that it chooses the letter a ?