SOLUTION: In a multiple-choice test, each question has five options. Students will get 10 points for each correct answer; lose 2 point for each incorrect answer; and receive no points for un

Algebra ->  Probability-and-statistics -> SOLUTION: In a multiple-choice test, each question has five options. Students will get 10 points for each correct answer; lose 2 point for each incorrect answer; and receive no points for un      Log On


   

Question 421429: In a multiple-choice test, each question has five options. Students will get 10 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.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
In a multiple-choice test, each question has five options.
Students will get 10 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.
-----
Random Values: 10 ; -2, ; 0
Probabilities: 1/4; 4/5 ; 0
------
E(x) = (1/5)10 - (4/5)2
---
E(x) = 2 - 8/5
---
E(x) = 10/5 - 8/5 = 2/5 = 0.4
----
She should guess
=======================
Cheers,
Stan H.
============