Question

The sum of first 31 terms of an arithmetic sequence is 620.
(a) What is its 16th term ?​

Answer 1

Answer:

20

Explanation:

First we take sum of 31 terms

Sn=n/2(2a + (n-1)d)

S31=31/2 (2a + 30d)=620

2a+ 30d=620×2/31

2a + 30d= 40

dividing the equation by 2 we get

a+15d = 20 (a16 = a + (16-1)d)