Packing the Lifts
Understand the puzzle
The exact puzzle
There are two lifts. Each lift can carry at most 30 kg. Seven riders are waiting. They weigh 6, 7, 9, 11, 13, 15, and 18 kg. You want as many riders as possible to go up together in the two lifts at once. What is the largest number of riders that can go up at the same time?
Why this matters
Notice when your first good idea is not the best idea
Take your time reading. There's no rush at all. Use the picture on the side to help it make sense, then tell me what it's really asking.