A. 5000
Feedback Let the sum be $ 100. Then,
SI = $ (100 × 6 × 2/100) = $ 12 and
compound interest = $ {100 × (1 + 6/100)² - 100}
= $ {(100 × 53/50 × 53/50) - 100} = $ (2809/25 - 100) = $ 309/25
Therefore, (CI) - (SI) = $ (309/25 – 100) = $ 9/25
If the difference between the CI and SI is $ 9/25, then the sum = $ 100
If the difference between the CI and SI is $ 18, then the sum = $ (100 × 25/9 × 18 ) = $ 5000
Hence, the required sum is $ 5000.