A student has heard that spinning pennies on a table, rather than flipping them in the air, results in tails side up 65% of the time. If this is true, what is the probability that a student who spins 4 pennies will have at least one land heads side up?

The easiest way to find the chance of at least one heads is to subtract the chance of getting no heads from 1. No heads means all 4 pennies land tails, so the probability is 0.65 × 0.65 × 0.65 × 0.65 = 0.1785. Therefore, the probability of at least one heads is 1 − 0.1785 = 0.8215, choice C.

AI-written and checked against the verified answer.