Answer:
1/2 or 50%
Explanation:
You can use some casework to find your answer.
The first case - only two of the coins are heads.
The possible ways that this could be are:
THH
HTH
HHT
The second case - all three coins are heads.
In this instance, there is only one way that this could happen:
HHH
This is a total of 4 desired outcomes out of 2*2*2=8 possible outcomes, which is a probability of 4/8=1/2. Hope this helps!