Posted by **Jen** on Wednesday, July 20, 2011 at 3:38pm.

In a multiple-choice test, each question has five options. Students will get 5 points for each correct answer; lose 2 point for each incorrect answer; and receive no points for unanswered questions. A student does not know the correct answer for one question. Is it to her advantage or disadvantage to guess an answer? Show your calculations for expected value.

- Math -
**bobpursley**, Wednesday, July 20, 2011 at 3:45pm
expected value of random choice: 1/5*5 + 4/5*(-2)=1-8/5

expected value of skipping, no answer: 0

so, skip it.

Now what if you could eliminate just one silly wrong answer?

expected value of guessing: 1/4*5-2(3/4)= 1.25-6/4=1.25-1.50=-.25

what if you could eliminate two silly answers....

expected value guessing=1/3*5 -2(2/3)= 5/3-4/3=.3333.

so, if you can't eliminate at least two answers, don't guess on this test. Normally on multiple choice, it is pretty easy to eliminate two answers.

- Math -
**Jen**, Thursday, July 21, 2011 at 7:48am
oh okay...so confusing...thank you.

## Answer This Question

## Related Questions

- Math - In a multiple-choice test, each question has five options. Students will ...
- Math-probability - In a multiple-choice test, each question has five options. ...
- Stat HW for. - 1. A student taking a midterm exam in Ancient History comes to ...
- Statistical concept 68-95-99.7 - 1. A student taking a midterm exam in Ancient ...
- Math - Kosuke wrote a mathematics contest consistingof 25 multiple choice ...
- elem alg - On a certain test, the student gets 3 points for each correct answer ...
- math help - I need help solving this math problem, please: Problem: Angela's ...
- Math - I need help solving this math problem, please: Problem: Angela's math ...
- Math - Sanjay takes a pre-ap multiple choice test of 25 questions in which he ...
- Math (Algebra) - Gretchen and Ezia received equal scores on a test made up of ...

More Related Questions