+174 John flips a penny, a nickel, and a dime. How many ways can she get at least two heads?
+981 Alright, here we go:
Since all we are talking about is heads or tails, what type of coin it is doesn’t matter.
There are a total of $2^3$ different outcomes when you flip three coins.
Here are all of them listed:
HHH ; HHT ; HTH ; THH ; TTT ; TTH ; THT ; HTT
Out of the eight different outcomes, only $\binom{3}{2}$ of them have 2 heads.
HHT, THH, and HTH
Since the problem is asking for at least, we can also get 3 heads, which there is only one way to do:
HHH.
There are 4 outcomes that match what the problem is asking for, so the answer is 4/8, 0.5, or 50%.
