SAT Math Multiple Choice Practice Question 536: Answer and Explanation
14. If one worker can pack 15 boxes every two minutes, and another can pack 15 boxes every three minutes, how many minutes will it take these two workers, working together, to pack 300 boxes?
Correct Answer: D
D The easiest way to solve this problem is to get to a common rate. You know that one packer packs 15 boxes every 2 minutes, and the other packs 15 boxes every 3 minutes. If you put these in terms of 6-minute intervals, the first packer will pack 45 boxes in 6 minutes, while the other packs 30 every 6 minutes. This means that together they will pack 75 boxes in 6 minutes, 150 boxes in 12 minutes, and 300 boxes in 24 minutes.