Question

The sum of the first 15 terms of an arithmetic sequence in 300. What is the 8th term?

Answer 1

Answer:

Given

a+7d =20

We know

Sum of first n terms= (n/2)[2a+(n-1)d]

=(15/2)[2*a+(15–1)*d]

=(15/2)[2a+14d]

=15(a+7d)

=15*20=300

So 300 is the sum of first 15 terms.

Answer 2

EXPLANATION

• GIVEN

Sum of 15 terms of ap = 300

FIND THE 8TH TERM

Sum of nth term =

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

S15 = 15/2 ( 2a + 14d ) = 300

2a + 14d = 40

a + 7d = 20

8th term of Ap

T8 = a + 7d

a + 7d = 20 given in above equation

a + 7d = 20

therefore,

8th term of ap = 20 = ANSWER