Find the sum of 6 + 8 + 10 + 12 + 14 ........... + 40.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 414
Sn = n/2 × (a + l)
40 = 6 + (n - 1) × 2
34 = (n - 1) × 2
n = 18.
S18 = 18/2 × (6 + 40)
= 9 × 46 = 414.