Question

An arithmetic series contains 20 numbers. The first number is 102. The last number is 159. Which expression represents the sum of the series?
A.(20 (159-102/2)
B.(20(102+159/2)
C.20(102+159)
D.20(159-102)

Answer 1

Answer:

Option B

Step-by-step explanation:

we know that

The sum of an arithmetic series is equal to

S=n(a1+an)/2

where

a1 is the first term

an is the last term

n is the number of terms

In this problem we have

n=20

a1=102

an=159

substitute the values in the formula

S=20(102+159)/2