Mathematics

Find the sum of the first 20 terms of the series 8, 12, 16, …..,…

Find the sum of the first 20 terms of the series 8, 12, 16, ….., 96

  • A.
    1400
  • B.
    1040
  • C.
    960
  • D.
    920
Correct Answer: Option D
Explanation

8, 12, 16, …..96
a = 8, d = 4, l = 96, n = 20
(S_{20} = frac{n}{2}(2a + (n-1)d)

(S_{20} = frac{20}{2}((2times 8) + (20-1)times 4))

(S_{20} = 10(16 + (19times 4)) = 10 times 92)

=920