The given series is a pattern-based numerical sequence: 1 : 1, 8 : 4, 9 : 27, 64 : 16, 25 : 125, ? : ?, 49 : 343. Our task is to identify the missing pair.
The sequence consists of pairs of numbers in the form x : y. Observe that in each pair, the x values are either perfect squares or perfect cubes, and the y values follow a specific relationship with the x values. Let's establish the pattern:
The pattern alternates between a perfect cube paired with a perfect square and vice-versa.
Thus, the missing pair, following the pattern, is 216:36.