Question

A multiple choice test has 12 questions each of which has 5 possible answers, only one of which is correct. If Judy, who forgot to study for the test, guesses on all questions, what is the probability that she will answer exactly 3 questions correctly?

Answer 1

To find the probability that Judy will answer exactly 3 questions correctly, you need to use combinations. There are C(12, 3) ways to choose 3 questions out of 12 to answer correctly. The probability of guessing a question correctly is 1/5, and the probability of guessing a question incorrectly is 4/5.

Step-by-step explanation:

To find the probability that Judy will answer exactly 3 questions correctly, we need to use the concept of combinations. There are C(12, 3) ways to choose 3 questions out of 12 to answer correctly.

The probability of guessing a question correctly is 1/5, and the probability of guessing a question incorrectly is 4/5. Since Judy is guessing on all questions, the probability of guessing 3 questions correctly is (1/5)^3 * (4/5)^(12-3).

Therefore, the probability that Judy will answer exactly 3 questions correctly is C(12, 3) * (1/5)^3 * (4/5)^(12-3).

Answer 2

4  out of 12 I hope this helps you