What is the probability of drawing a twenty-dollar bill?

​A wallet containing 5 five‑dollar bills, 7 ten‑dollar bills, and 8 twenty‑dollar bills is found and returned to its owner. The wallet’s owner will reward the finder with 1 bill drawn randomly from the wallet. What is the probability that the bill drawn will be a twenty-dollar bill?

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# of successes 
----------------- = probability
# of possibilities

8 twenties
------------- = probability of drawing a twenty
20 total bills

=  2/5  {reduced}

=  0.4  or 40%  {divided}

Probability could be thought of as  0.4 or 40%.

Ask the House
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