Help with Probability Word Problem6

Algebra
Tutor: None Selected Time limit: 1 Day

Three fair coins are tossed. What is the probability that at least one is a head? (Enter the probability as a fraction.)

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Dec 2nd, 2014

all possible outcomes on 3 coins are: 
3 heads: HHH --> 1 outcome
2 heads: HHT or HTH or THH --> 3 outcomes
1 head: HTT or THT or TTH --> 3 outcomes
0 heads: TTT --> 1 outcome 


Question asks for at least 1 head which is any of the top 7 outcomes. 

Now each of these outcomes has a probability of (1/2)*(1/2)*(1/2) --> 1/8 since we have 3 coins flipped at a time. 

So the answer is 7/8. In other words, it is highly likely to get at least one head when flipping 3 coins. The only time you would not is by getting 3 tails. 

Jon

Dec 2nd, 2014

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Dec 2nd, 2014
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