An unfair coin has a probability of coming up heads of 0.55 the coin is tossed 4 times. What is the probability that it lands heads at least once?

1-P(no heads) = 1-.45^4

To find the probability of getting at least one head when tossing a biased coin multiple times, we can use the concept of complementary probability.

The probability of an event happening is equal to 1 minus the probability of the event not happening. In this case, the event we are interested in is getting at least one head.

To calculate the probability that the coin lands heads at least once, we need to find the probability of not getting any heads in all four tosses and subtract it from 1.

The probability of getting tails on a single toss is 1 - 0.55 = 0.45, because the sum of the probabilities of heads and tails must equal 1.

Therefore, the probability of getting tails on all four tosses is (0.45) * (0.45) * (0.45) * (0.45) = 0.45^4.

To find the probability of getting at least one head, we subtract the probability of never getting heads from 1:

1 - 0.45^4 = 1 - 0.091125 = 0.908875.

So, the probability that the unfair coin lands heads at least once in four tosses is approximately 0.909 or 90.9%.