SOLUTION: A boy has three 10-cent coins and five 5-cent coins in his pocket. The boy draws four coins for good luck. Calculate the probability of the event that the coins drawn will be enoug
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Question 1198728: A boy has three 10-cent coins and five 5-cent coins in his pocket. The boy draws four coins for good luck. Calculate the probability of the event that the coins drawn will be enough to pay 30 cents for the purchase. Answer by ikleyn(52878) (Show Source):
You can put this solution on YOUR website! .
A boy has three 10-cent coins and five 5-cent coins in his pocket.
The boy draws four coins for good luck. Calculate the probability
of the event that the coins drawn will be enough to pay 30 cents for the purchase.
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Favorable outcomes are THESE:
10-cent 5-cent Total Total
coins coins coins cents
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3 1 3+1 = 4 3*10+5 = 35 > 30
2 2 2+2 = 4 2*10 + 2*5 = 30
There is no other favorable combination for the given conditions.
So, the number of all favorable outcomes is 2.
The number of all possible outcomes is the number of all possible quadruples of 3+5 = 8 coins,
i.e. = = 70.
So, the probability under the problem's question is
P = = = . ANSWER
Solved and carefully/thoroughly explained.
In this problem, the order/(ordering) of coins does not matter, so we use COMBINATIONS.
