Question

The probability that a grader will make a marking error on any particular question of a multiple-choice exam is 0.10. If there are ten questions and questions are marked independently, what is the probability that no errors are made

Answer 1

0.9^10

Explanation:

The probability to make an error in 1 question =0.1 => The probability that this one particular question will be answered correctly is P=1-0.1=0.9

There are 10 questions that are independent from each other .

The probability to be answered correctly is 0.9 each. So the probability to answer correctly to all of them is

P(10quest=correct) =0.9*0.9*0.9*0.9*0.9*0.9*0.9*0.9*0.9*0.9=0.9^10