Question

The probability of guessing the correct answer to a certain test questions is $\frac{x}{12}$. If the probability of not guessing the correct answer to this question is $\frac{2}{3}$, then x =

(a) 2

(b) 3

(c) 4

(d) 6

Answer 1

GIVEN: Probability of guessing a correct answer to a certain question is

Probability of not guessing a correct answer to a same question

TO FIND: The value of x

CALCULATION: We know that sum of probability of occurrence of an event and probability of non occurrence of an event is 1.

If E is an event of occurrence and is its complementary then

According to the question we have

Hence the correct option is