SAT Math Multiple Choice Question 837: Answer and Explanation
12. Each crop duster who works for Gary's Crop Dustin' 4 Cheap can dust half an acre ofcrops in 25 minutes. The company must dust eight 0.75-acre lots and twelve 1.5-acrelots to complete a certain job. What is the minimum number of crop dusters neededto complete the job in 5 hours?
- A. 4
- B. 5
- C. 6
- D. 7
Correct Answer: A
Category: Problem Solving and Data Analysis / Rates, Ratios, Proportions, and Percentages
Strategic Advice: Questions that involve rates, especially rates related to time, often require logical thinking rather than the use of an algebraic equation.
Getting to the Answer: Start by determining how many acres need dusting: acres. One crop duster can dust half an acre in 25 minutes, or a whole acre in 50 minutes. Thus, if one duster were to do the whole job, it would take 24 acres × 50 minutes/acre = 1,200 minutes which is hours. However, the job needs to be completed in 5 hours, which is of 20. To get the job done in only one-quarter the time, Gary's needs to use 4 × 1 = 4 crop dusters, choice (A).