What is the sum of the following series?

- 64, - 66, - 68, …… , - 100

- - 1458
- - 1558
- - 1568
- - 1664
- None of the above

**Solution**

The series is Arithmetic Progression with

First term = -64

Last term = -100

Common difference = -2

T_{n} = a + (n-1)d

-100 = -64 + (n-1)*(-2)

n-1 = 36/2 = 18

n = 19

This series has 19 negative numbers, where all the numbers in the series is 2 less than previous number.

Sum = n/2 [a+l]

= 19/2 [- 64 - 100] = - 1558

**The correct option is B.**