Question

If you guess the answers at random, what is the probability of getting at least two correct answers on a five-question true-or-false quiz?

Answer 1

Since each question only has two outcome, which is yes/no. A five question true/false quiz is consist of five true/false factors.

True/false can be simulated as 1/2, or half the change of being correct.

Now if you put 1/2 to it’s fifth power, or (1/2)^5, since there are five questions.

The chances of getting ALL FIVE questions right is 1/32, now if you want to have two questions correct, which is 2/5 of the probability, then we would only need to raise the power to 3, since you we’re considering the other three would be definitely wrong

(1/2)^3 = 1/8
In result, the probability of getting 2 out of 5 questions correct is 1/8