### Instruction: Suppose we flip four coins simultaneously: a penny, a nickel, a dime, and a quarter.  What is the probability that they all come up heads?### Response: To find the probability of a compound event, we can multiply the probabilities of each individual event, assuming they are independent.
Flipping a coin is an independent event, meaning that the outcome of one coin does not affect the outcome of another coin.
The probability of getting heads on any one coin is 1/2, since there are two equally likely outcomes: heads or tails.
Therefore, the probability of getting heads on all four coins is (1/2) * (1/2) * (1/2) * (1/2), which is 1/16.
We can write this as a fraction or as a decimal: 0.0625.