You and your brother always flip a special golden dollar coin to decide who gets to select the music when the two of you are in the car. The coin has come up heads (in your brother’s favor) on 8 of the last 10 flips. Do 10 flips provide convincing evidence that your brother is using an unfair coin to gain an advantage?

A fair coin has a 0.5 chance of heads on each flip, so 10 flips would average 5 heads—but it would not have to produce exactly 5. Getting 8 heads can happen by chance, and 10 flips is a small sample, so it is not convincing evidence by itself that the coin is unfair. The best choice is “No, 10 trials (flips) is not enough evidence to determine if the coin is fair.”

AI-written and checked against the verified answer.