Answer:
2 Heads: 1/4
At least 1 Head: 3/4
Explanation:
The way that we solve for combined probabilities is by multiplying the single probabilities together.
The probability of tossing a coin and getting heads = 1/2
1/2 x 1/2 = 1/4
This makes sense, since HH is only one outcome out of the 4 possible:
HH TT HT TH
The other probability, at least one head, based on counting the probabilities with heads in them is 3/4. Only the TT option has no heads.