The following practice questions are similar to what you'll run into: first, you have to calculate the probability of drawing a certain card from a 52-card deck; then, you put on an epidemiologist's hat and try to figure out the odds that a certain student is feeling under the weather during a class field trip.
Practice questions
- In drawing cards from a 52-card deck, any single card has an equal chance of being drawn. After six cards have been drawn and removed, what is the probability of drawing an ace of hearts if it has not yet been drawn?
A. 1:50 B. 1:48 C. 1:46 D. 1:44
The next question is based on the following situation: Forty tenth grade social studies students are on a field trip, but many of the students don't feel well. Ten students are healthy, but each of the remaining thirty has a sore throat, a stomach virus, or both.
- If a student is selected randomly from the whole group, what is the probability that he or she has a sore throat?
A. .275 B. .375 C. .475 D. .575
Answers and explanations
- The correct answer is Choice (C).
You're asked to figure out the probability of an event occurring. If you had an entire deck of 52 cards, the probability of drawing an ace of hearts would be 1:52. If you remove 6 cards and none of them is the ace of hearts, you may as well have a 46-card deck (52 – 6). The probability of drawing an ace of hearts from a 46-card deck is 1:46.
- The correct answer is Choice (B).
To calculate the probability that a random student will have a sore throat, divide the number of students that have a sore throat by the total number of students.
