The fountain contains 20 pennies and 9 dimes. A coin is randomly taken and not replaced. A second coin is randomly taken. What is the probability that both coins are pennies?

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Well, the first coin has chance [latex]\frac{20}{29}[/latex] to be a penny. When it is a penny, the only valid case (the other case gives 0 for the multiplications later, so it is ignored) gives [latex]\frac{19}{28}[/latex] chance for the second one to be a penny. The result is [latex]\frac{20*19}{29*28}[/latex], which is [latex]\frac{95}{203}[/latex], or about 46.80% (rounded to the first 2 decimals)

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