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