A student has heard that spinning pennies on a table, rather than flipping them in the air, results in tails side up 65 percent 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?

It is easiest to use the opposite event: the only way to have no heads is for all 4 pennies to land tails. Assuming the spins are independent, that probability is 0.65⁴ = 0.17850625. So the probability of at least one heads is 1 − 0.17850625 = 0.82149375, or about 0.8215. This matches choice C, 0.8215.

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