Answer:
1 in 8 chance.
Explanation:
When a coin flips is has two outcomes: heads or tails, obviously.
Whenever you have a 50/50 probability, in this case a coin, every time you add another coin the amount of outcomes squares, or multiplies by the number of outcomes, and since we are using a coin, two. To reiterate, say we were using a die, a die is a cube, a six sided shape, so there are six outcomes. The chances of getting all sixes with one die is 1 in 6. Add another die and try to get all sixes, the chances become 1 in 36. We got this by multiplying our out comes by our outcomes
1 coin: 2 outcomes
2 coins: 4 outcomes
3 coins: 8 outcomes
Another thing:
Don't be fooled by questions being specific by saying "all heads" or "all tails"...
This is a wording trick, no matter the outcome, the chances will always be equal.
Good luck :)