Question

find the number of terms in the series 20, 19 1/3, 18 2/3.... of which the sum is 300 find the 31st term
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Answer 1

Step-by-step explanation:

1th

Maths

Sequences and Series

Sum of n Terms of Special Series

Find the number of terms in...

MATHS

Find the number of terms in the series 20+19

3

1

+18

3

2

+.... of which the sum is 300, explain the double answer.

MEDIUM

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ANSWER

The given series is an arithmetic series with first term a(=20) and the common difference d(=−

3

2

).

Let the sum of n terms be 300.

Then, S

n

=300

⟹

2

n

{2a+(n−1)d}=300

⟹

2

n

{2×20+(n−1)(−2/3)}=300

⟹n

2

−61n+900=0⟹(n−