Question

what is the probability that at least two of the coins will be tails?
1/8
3/8
1/2
3/4

Explanation:

Step1: Count total outcomes

From the tree - diagram, the total number of possible outcomes when flipping 3 coins is 8.

Step2: Count favorable outcomes

The outcomes with at least two tails are (H,T,T), (T,H,T), (T,T,H), (T,T,T). So there are 4 favorable outcomes.

Step3: Calculate probability

The probability $P$ of an event is given by $P=\frac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}}$. So $P = \frac{4}{8}=\frac{1}{2}$.

Answer:

$\frac{1}{2}$