The A. P. Statistics exam consists of a multiple-choice section in which each question has five choices. Sara estimates that she has a 75% chance of knowing each question. If she does not know the answer, she will randomly guess.

a) What is the probability of Sara getting a question correct?

b) The A. P. exam has 40 questions, how many might Sara expect to get correct?

Question

Mathematics

Carter Chase

4 August, 06:34

The A. P. Statistics exam consists of a multiple-choice section in which each question has five choices. Sara estimates that she has a 75% chance of knowing each question. If she does not know the answer, she will randomly guess.

a) What is the probability of Sara getting a question correct?

b) The A. P. exam has 40 questions, how many might Sara expect to get correct?

+4

Answers (1)

Know the Answer?

Savannah Gross · Answer 1

A)

75% she knows for sure

Out of the remaining 25%, she has a 1/5 or 20% chance of getting it right. So,

1/4 x 1/5 x 100 = 5%

Total chance of getting a question right:

75 + 5 = 80%

b) If the total is 40, she can expect to get

80% x 40 = 32 questions correct.