16Hit1600
AlgebraHardInterpreting a rate of sale

Algebra practice question

The function N(t) = 250 − 15t models the number of tickets still unsold t hours after sales open. Which of the following is the best interpretation of the number 15 in this context?

  1. A. About 15 tickets are sold each hour.Correct
  2. B. 15 tickets remain unsold at the end.
  3. C. The tickets sell out after 15 hours.
  4. D. Sales are open for 15 hours.

Answer: A. About 15 tickets are sold each hour.

The coefficient of t is the change per hour; N falls by 15 each hour.

Why the other answers are wrong

B. 15 tickets remain unsold at the end.
The number left depends on t, not on the coefficient.
C. The tickets sell out after 15 hours.
Selling out takes 250/15, about 16.7 hours.
D. Sales are open for 15 hours.
Nothing in the model sets the opening hours.

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