Q12 / 118 · NTA Abhyas (JEE Main) 2020 · Mathematics · Sequences and Series

The sum of four numbers in an arithmetic progression is 48 and the ratio of the product of the extremes to the product of the two middle terms is 27:35, then the largest term of this arithmetic progression is

  • A
    10
  • B
    12
  • C
    14
  • Correct answer
    D
    18

Solution

Let the A. P. be a-3d, a-d, a+d, a+3d
The sum of the terms =48=4a⇒a=12
Given, 12-3d12+3d12-d12+d=2735
⇒94-d4+d12-d12+d=2735
⇒16-d235=144-d23
⇒35d2-3d2=16×35-144×3
⇒32d2=1635-27=16×8
⇒d2=4⇒d=±2
So the numbers are: 6,10,14,18

Hence, the correct answer is option: 'D'.

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