A fair coin is flipped 7 times. What is the probability of obtaining at least 1 tail?

Question

Give answer as a decimal number with 3 correct decimal places. Show work!

Answer 1

1. The only way that there would not be at least 1 tail is if all seven of the coin flips came up heads.
2. P[heads] = 1/2
3. P[seven heads in seven flips] = (1/2)⁷
4. P[at least one tail] = 1 - P[seven heads in seven flips]  =  1- (1/2)⁷
5. I will let you handle rounding to three decimal places