SOLUTION: A box contains 8 dimes, 15 quarters, and 27 nickels. A student randomly draws two items, one at a time without replacement, from the bag. Find the probability that 2 quarters are d
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-> SOLUTION: A box contains 8 dimes, 15 quarters, and 27 nickels. A student randomly draws two items, one at a time without replacement, from the bag. Find the probability that 2 quarters are d
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Question 1139892: A box contains 8 dimes, 15 quarters, and 27 nickels. A student randomly draws two items, one at a time without replacement, from the bag. Find the probability that 2 quarters are drawn. Found 2 solutions by ikleyn, greenestamps:Answer by ikleyn(52805) (Show Source):
The total number of coins is 8 + 15 + 27 = 50.
The probability to draw a quarter at the first drawing is = .
The probability to get a quarter at the second drawing is = .
The probability under the question is therefore the product = = = . ANSWER
The solution by tutor @ikleyn is a perfectly good solution using basic ideas of probability.
You should understand that method and know how to use it.
Here is a solution by a different method that is bit more difficult than her method for this problem but can be an easier method to use when similar problems get more difficult.
You should also understand and be able to use this method for similar problems.
The total number of ways of choosing 2 of the 50 coins in the box is "50 choose 2"; the number of ways of choosing 2 of the 15 quarters is "15 choose 2". The probability of getting 2 quarters when 2 coins are randomly drawn from the box is
