Question

Sarah and Paula are flipping coins. During each round, each one flips a fair coin and then they compare their results. What is the probability that both girls flip their first tails during the same round?

Answer 1

Answer:

$1/3$

Step-by-step explanation:

The rounds that give two heads can be neglected.

Looking at the first round that gives at least one tail let T

denotes the number of tails is that round

$P(T=2\mid T\geq1)=\frac{P(T=2)}{P(T\geq1)}=\frac{1/4}{3/4}=\frac13$