Problem

A student is taking a standardized test consisting of several multiple-choice questions. One point is awarded for each correct answer. Questions left blank neither receive nor lose points. There are four options for each question and the student is penalized $\frac{1}{9}$ point for each wrong answer. Is it in the student's best interest to guess? Explain.

Answer

Expert–verified
Hide Steps
Answer

Final Answer: Yes, it is in the student's best interest to guess. The expected value of guessing is approximately \(\boxed{0.167}\), which is a positive value. This means that on average, guessing will result in a net gain of points for the student.

Steps

Step 1 :The problem is asking whether it is beneficial for a student to guess on a multiple-choice test, given the scoring system. To answer this, we need to calculate the expected value of a guess. The expected value is the average outcome of an event if it were to be repeated many times. In this case, the event is guessing on a question.

Step 2 :There are four possible outcomes when guessing: The student guesses correctly, which happens with probability \(\frac{1}{4}\) and results in a gain of 1 point. The student guesses incorrectly, which happens with probability \(\frac{3}{4}\) and results in a loss of \(\frac{1}{9}\) point.

Step 3 :We can calculate the expected value by multiplying each outcome by its probability and summing these products. If the expected value is positive, it is in the student's best interest to guess. If it is negative, it is not in their best interest to guess. If it is zero, guessing neither helps nor hurts the student on average.

Step 4 :Let's calculate the expected value: \(p_{correct} = 0.25\), \(p_{incorrect} = 0.75\), \(correct = 1\), \(incorrect = -0.1111111111111111\), \(expected_{value} = 0.16666666666666669\)

Step 5 :The expected value of guessing on a question is approximately 0.167. This is a positive value, which means that on average, guessing will result in a net gain of points for the student. Therefore, it is in the student's best interest to guess on the test.

Step 6 :Final Answer: Yes, it is in the student's best interest to guess. The expected value of guessing is approximately \(\boxed{0.167}\), which is a positive value. This means that on average, guessing will result in a net gain of points for the student.

link_gpt