A shoe shop in Indore has two shelves on its rack; the number on each shoe is its size. What is the mode of the shoe sizes on the WHOLE rack?

Count across both shelves: size 5 once, 6 three times, 7 four times (2 on each shelf), 8 three times, 9 once. The most frequent size is 7. Each shelf alone has a different mode (6 and 8), which is the trap; 4 is the frequency, not the size.