Identify the series that is different from the rest.

Logic: 1st number = (2nd number)² and 2nd number = (3rd number)²​

Now, we check each options.

Option (a): 0.0016, 0.04, 0.2 (Follow)

0.0016 = (0.04)² and 0.04 = (0.2)²​

Option (b): 243, 81, 27 (Not Follow)​

243 = 3⁵, 81 = 3⁴, 27 = 3³​

Option (c): ​$$\frac{1}{16},\frac{1}{4},\frac{1}{2}$$ (Follow)​

​$$\frac {1}{16}$$​ = $$\Big (\frac {1}{4}\Big )$$​² and $$\frac {1}{4}$$​ =$$\Big (\frac {1}{2}\Big)$$​²

Option (d): 2401, 49, 7 (Follow)​

2401 = (49)² and 49 = (7)²​

So, the different is option (b)

Thus, correct option is (b).