SAT Math Multiple Choice Question 623: Answer and Explanation
8. One bag of grass seed can cover 5,000 square feet of new lawn. If each bag costs p dollars, which of the following expressions gives the cost, in dollars, to cover a new rectangular lawn that measures a feet by b feet?
- D. 5,000abp
Correct Answer: B
Algebra (word problems) MEDIUM
Perhaps the most straightforward way to approach this question is to regard it as a conversion from a given area of lawn (in square feet) to cost (in dollars).
Area of rectangular lawn:
A = bh = ab square feet
Convert using given conversion factors:
Make sure to check this calculation by noticing that all units "cancel" as common factors, except for the unit we want, dollars, which remains in the numerator.