A wallet contains five $10 bills, four $5 bills, and six $1 bills (nothing large

Question

A wallet contains five $10 bills, four $5 bills, and six $1 bills (nothing larger). If the bills are selected one by one in random order, what is the probability that at least two bills must be selected to obtain a first $10 bill?

How should this be interpreted? That the first two bills will not be a $10? That the second bill will be a $10?

Please do not just repost the exact same answers that are already on chegg. I have seen them, they are not helpful. Explain how to solve it with principles of probability.

Explanation / Answer

If the bills are selected one by one in random order, what is the probability that at least two bills must be selected to obtain a first $10 bill?

P ( at least 2 bills must be selected to obtain a first $10 bill)

you have that only 2 of $5 and 5 of $1 with 1 of $5 will you have a value of $10

so the probability is   4C2 / 15C2   +    4C1 * 6C5 / 15C6 = 0.05714 + 0.004795 = 0.061935

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