The cost of mining a ton of coal is rising faster every year. Suppose is the cost of mining a ton of coal at time t. Which of the following must be positive? Select all that apply.

Question

The cost of mining a ton of coal is rising faster every year. Suppose  is the cost of mining a ton of coal at time t. Which of the following must be positive? Select all that apply.

Quizplus · Accepted Answer

Since the cost of mining a ton of coal is rising every year, the cost at a later time must be greater than the cost at an earlier time. Therefore, all of the given options must be positive.

The Cost of Mining a Ton of Coal Is Rising