sat suite question viewer
| 00–99 years | 1010–1919 years | 20+20+ years | Total | |
|---|---|---|---|---|
| Group A | 77 | 1414 | 9 | 30 |
| Group B | 6 | 4 | 20 | 30 |
| Group C | 17 | 12 | 1 | 30 |
| Total | 30 | 30 | 30 | 90 |
The table summarizes the distribution of age and assigned group for participants in a study.
One of these participants will be selected at random. What is the probability of selecting a participant from group A, given that the participant is at least years of age? (Express your answer as a decimal or fraction, not as a percent.)
Explanation
The correct answer is . It's given that one of the participants will be selected at random. The probability of selecting a participant from group A given that the participant is at least years of age is the number of participants in group A who are at least years of age divided by the total number of participants who are at least years of age. The table shows that in group A, there are participants who are – years of age and participants who are years of age. Therefore, there are , or , participants in group A who are at least years of age. The table also shows that there are a total of participants who are – years of age and participants who are years of age. Therefore, there are a total of , or , participants who are at least years of age. It follows that the probability of selecting a participant from group A given that the participant is at least years of age is . Note that 23/60, .3833, and 0.383 are examples of ways to enter a correct answer.