you flip a coin. what is p(not heads)?

Explanation:

Step1: Identify total outcomes

A coin - flip has 2 possible outcomes (heads or tails).

Step2: Identify favorable outcomes

The event of "not heads" means getting tails, which is 1 outcome.

Step3: Calculate probability

The probability formula is $P(A)=\frac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}}$. So $P(\text{not heads})=\frac{1}{2}$.

Answer:

$\frac{1}{2}$