Hi,

I just did a test which had two multiple choice questions. Each question was worth one point. Getting them both right would result in getting a 100% score. Suffice it to say, getting just one question right would give you 50% and with that a passing grade.

So you have two multiple choice questions. Both of which are unrelated to the other. Each question has four possible answers. When you finish the test. You get to have one more try. The questions and possible answers remain the same.

Let’s say you use both tries and you remember your previous two respected answers. What would your odds be, if you were to brute force guess your way through this test, to get a passing grade or a 100%?

Edit: Both questions only have one correct answer.

IMPORTANT EDIT: YOU DO NOT KNOW WHICH ANSWER YOU HAD RIGHT OR WRONG THE SECOND TIME AROUND. You only know how many questions you got right. But you don’t know which. Sorry for the confusion!

  • pruwyben@discuss.tchncs.de
    1·
    11 months ago

    For a passing grade - the easy way to calculate it is by calculating the chance of failing and then subtracting it from 1. To fail, you need to get the first two questions wrong (3/4 times 3/4) and then get them both wrong again on the second try (2/3 times 2/3 since you are choosing from the remaining 3 choices for each). So 3/4 x 3/4 x 2/3 x 2/3 = 1/4 or 25%, so you have a 75% chance of passing.