Two students arrive late for a math final exam with the excu

Two students arrive late for a math final exam with the excuse that their car had a flat tire. Suspicious, the professor says “each one of you write down on a piece of paper which tire was flat. What is the probability that both students pick the same tire?

Solution

for each students have a probability of 1 /4 to pick one flat tire

but as you can see there are 2 students and we need the probability of both students pick the same tire

so the probability is 1/4 * 1/4 = 1/8

Porbability = 1/8