NIMCET 2020 Question Paper with solutions

Question : 19 of 120

Marks: +1, -0

An arithmetic progression has 3 as its first term. Also, the sum of the first 8 terms is twice the sum of the first 5 terms. Then what is the common difference?

$3/4$
$1/2$
$1/4$
$4/3$

Validate

Solution:

a=3,S_8=2.S_5

(given)

8/2[2.3+(8-1)d]=2. 5/2[2.3+(5-1)d]

4[6+7d]=5[6+4d]

=24+28d=30+20d

⇒8d=6

d=3/4

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