Answer:
-0.125.
Step-by-step explanation:
Prob(correct answer) = 1/4 = 0.25 , Prob(wrong answer) = 0.75.
Expected value = 1 * probability of a correct answer - 0.5 * probability of an incorrect answer.
= 1 * 0.25 - 0.5 * 0.75
= -0.125
