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Count the square tiles
Use the complete repeating unit to count the tiles.
A path is 30 m long and 25 cm wide. It is paved with a pattern that repeats along its length: two square tiles of side 25 cm, then one rectangular tile measuring 20 cm by 25 cm. Only complete repeats are laid, and any length left at the end is left bare. How many square tiles are used?
Show the step-by-step solution
- length of the path = 30 × 100 = 3000 cm
- one repeat = 25 + 25 + 20 = 70 cm
- 43 repeats = 43 × 70 = 3010 cm, which is longer than the path
- 42 repeats = 42 × 70 = 2940 cm
- length left = 3000 - 2940 = 60
- 60 cm is less than one repeat, so no more tiles are laid
- square tiles = 42 × 2 = 84
Ans: 84