Unit 8, Lesson 9
Using Tables for Conditional Probability
Integrated Math 2
Practice
Problem 1
A tour company makes trips to see dolphins in the morning and in the afternoon. The two-way table summarizes whether or not customers saw dolphins on a total of 100 different trips.
| morning | afternoon | |
|---|---|---|
| dolphins | 39 | 34 |
| no dolphins | 5 | 22 |
- If a trip is selected at random, what is the probability that customers did not see dolphins on that trip?
- If a trip is selected at random, what is the probability that customers did not see dolphins under the condition that the trip was in the morning?
- Are the events of seeing dolphins and the time of the trip (morning or afternoon) dependent or independent events? Explain your reasoning.
Problem 2
Noah is unsure whether the coin and number cube he has are fair. He flips the coin then rolls the number cube and records the result. He does this a total of 50 times. The results are summarized in the table.
| one | two | three | four | five | six | |
|---|---|---|---|---|---|---|
| heads | 5 | 3 | 5 | 3 | 10 | 1 |
| tails | 3 | 4 | 5 | 2 | 7 | 2 |
- Create a two-way table that displays the probability for each outcome based on Noah’s tests.
- If one of Noah’s 50 results is selected at random, what is the probability that the coin was heads?
- If one of Noah’s 50 results is selected at random, what is the probability that the number cube was 5?
- Do you think the coin is fair? Do you think the cube is fair? Explain your reasoning.