Question

g In a math test, each multiple choice question has 4 selections (only one of them is the correct answer). A correct answer will earn 4 points and an incorrect is subject to 1 point deduction. What point is expected if a question is answered by random guessing

Answer 1

0.25

Explanation:

Given that:

Number of options per question = 4

Number of correct answer per question = 1

Number of incorrect answers per question = 3

By random guess:

Probability of picking a correct answer :

Number of correct answers / number of options

= 1 / 4 = 0.25

Probability of picking an incorrect answer :

Number of incorrect answers / number of options

= 3/4

Hence,

X :______ 4 _____ - 1

P(X) : ___ 0.25 __ 0.75

Σ(X*P(x))

(4 * 0.25) + (-1 * 0.75)

1 + (-0.75)

1 - 0.75

= 0.25