Question

Mr. Brown bought a television set and paid $110 as the first installment. If he increases each payment by $20 and pays a total of 6 installments, how much will the television set have cost him?

Answer 1

960

Explanation:

Answer 2

That answer is completely wrong. The correct answer is $960.

I'll show the work to prove and include the formulas I used.

First Step: Arithmetic sequence formula;

110(n-1)(20)

=110-20+20n

=90+20n

=90+20(6)

=210

Next Step: Arithmetic series formula

=6(110+210/2)

=6(320/2)

=6(160)

=$960