The volume of a pyramid is given by the formula (1)/(3) x base area x height.

Here are the solutions to the questions:

13. The volume of a pyramid is given by the formula $\frac{1}{3} \times \text{base area} \times \text{height}$.
The correct option is A.

• The volume of a pyramid is one-third of the area of its base multiplied by its height.

14. The sample space when tossing a fair coin once is the set of all possible outcomes. For a single coin toss, these are Heads (H) and Tails (T).
The correct option is B.

• The sample space for a single coin toss is $\{H, T\}$.

15. The probability of an event that will definitely occur is 1.
The correct option is C.