If 10 spiders can catch 10 files in 10 min, then how many

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If 10 spiders can catch 10 files in 10 min, then how many flies can 200 spiders catch in 200 min ?

1. 2000
2. 5000
3. 4000
4. 3000

Correct Option: C

Let the required number of flies be N.
More spiders, More flies (Direct proportion)
More time, More flies (Direct proportion)
∴ 10 x 10 x N = 200 x 200 x 10
∴ N = (200 x 200 x 10)/(10 x 10) = 4000 flies