Answer: 1/8
1 goes in the green blank space
8 goes in the gray blank space
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Step-by-step explanation:
H = heads
T = tails
HHH means we get 3 heads in a row, HHT means heads twice then tails the third time, and so on.
Here are the 8 ways to flip three coins (note: 2^3 = 2*2*2 = 8).
- HHH
- HHT
- HTH
- HTT
- THH
- THT
- TTH
- TTT
We see that HHH only comes up once out of 8 total times. Therefore, the probability of getting HHH is 1/8
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Another way to see the answer is note that P(H) = 1/2 is the probability of getting heads on a single coin flip
Then with two coin flips, we have P(HH) = P(H)*P(H) = (1/2)*(1/2) = 1/4. Each coin flip is independent of one another.
And finally, P(HHH) = P(H)*P(H)*P(H) = (1/2)*(1/2)*(1/2) = 1/8