Question

The given series has six terms. what is the sum of the terms of the series? 10 + 25 + 40 + . . . + 85

Answer 1

10+25+40+55+70+85
35+95+155
130+155
285

answer: 285

Answer 2

Answer with Step-by-step explanation:

The sum of first n terms of an arithmetic progression is given by:

`S(n)=(n)/(2)* (A1+An)`

10+25+40+...+85

Since, the terms have a common difference of 15

So, it is an arithmetic progression of n=6 terms with first term A1=10

and A6=85

We have to find S(6)

`S(6)=(6)/(2)* (10+85)`

= 285

Hence, the sum of the terms of the series 10 + 25 + 40 + . . . + 85 is:

285