Question

The sum of the first ten terms of an arithmetic sequence is four times the sum of the first five terms. What is the ratio of the second term to the first?

Answer 1

Step-by-step explanation:

Using S=

2

n

[2a+(n−1)d],

we have

2

10

(2a+9d) =4×

2

5

(2a+4d)

∴d=2a;∴a:d=1:2.