An unfair coin has a 45% chance of coming up tails. So this means that I have a 45% chance of tails, which also means, and we have to be careful here because they're asking us about heads, if I have a 45% chance of getting tails, that means I have a 55% chance of getting heads. Whatever, I have 100% chance of getting one of these two. If it's 45% for tails, 100 minus 45 is 55 for heads. For the fair coin, I have a 50% chance of tails and a 50% chance of heads. Fair enough. Now, I want to know, in either of these scenarios, what is the percent probability of getting four heads?