A test consists of 18

a. True

b. False questions. to pass the test a student must answer at least 13 questions correctly. if a student guesses on each question, what is the probability that the student will pass the test?

A. True. about 10% because if you guess on every question you might not pass the test.

Number of questions = 18

Find each of the probability:

P (13 correct) = 18C13 (0.5) ¹⁸ = 8568 / 262144

P (14 correct) = 18C14 (0.5) ¹⁸ = 3060 / 262144

P (15 correct) = 18C15 (0.5) ¹⁸ = 816 / 262144

P (16 correct) = 18C16 (0.5) ¹⁸ = 153 / 262144

P (17 correct) = 18C17 (0.5) ¹⁸ = 18 / 262144

P (18 correct) = 18C18 (0.5) ¹⁸ = 1 / 262144

Find sum of the above probability:

Find P (≥ 13 correct) = (8568 + 3060 + 816 + 153 + 18 + 1) / 262144

Find P (≥ 13 correct) = 12616/262144

Find P (≥ 13 correct) = 1577/32768

Find P (≥ 13 correct) = 0.048

Answer: 0.048