Given that (1<sup>2</sup> + 2<sup>2</sup> + 3<sup>2</sup> + ..... + 20<sup>2</sup>) = 2870, the value of (2<sup>2</sup> + 4<sup>2</sup> + 6<sup>2</sup> + ... + 40<sup>2</sup> ) is :

Correct Answer: 11480
= (22 +42 +62 + ..... + 402)
= (1 × 2)2 +(2 × 2)2 +(2 × 3)2 + ..... + (2 × 20)2
= 22 × (12 + 22 + 32 + ..... + 202)
= (4 × 2870)
= 11480