5 : 3125 :: 7 : ?

The correct answer is Option (3) → 16807

The rule is found from the first pair and then applied to the second: the second number is the fifth power of the first.

• \(5^{5}=5\times5\times5\times5\times5=3125\)

• \(7^{5}=7\times7\times7\times7\times7=16807\)

The other options are lower or higher powers of 7: \(343=7^{3}\), \(2401=7^{4}\), \(117649=7^{6}\).