Question

A coin is thrown 3 times. List out the sample space. What is the probability that at least one head is obtained?

Answer 1

When you flip a coin 3 times, then there are $2^3=8$ possible outcomes.

$$S=\{HHH, HHT, HTH, THH,$$

$$HTT, THT, TTH, TTT\}$$

$$P(at\ least\ 1\ H)=1-P(3\ T)=1-\dfrac{1}{8}=\dfrac{7}{8}$$