Description for Correct answer:
Let the required number of files be

More spiders, More flies (Direct proportion)

More time, More flies (Direct Proportion)

Spiders 10 : 200 )

Time 10 : 200 ) :: 10 : x

Therefore, \( \Large \left(10 \times 10 \times x\right) = \left(200 \times 200 \times 10\right) \)

Therefore, x = \( \Large \frac{200 \times 200 \times 10}{10 \times 10} \) = 4000 files