Q37 / 90 · JEE Main 2023 (13 Apr Shift 1) · Mathematics

Let s1,s2,s3....,s10 respectively be the sum of 12 terms of 10 A.Ps whose first terms are 1, 2, 3,....,10 and the common differences are 1, 3, 5,...,19 respectively. Then ∑i=110si is equal to

  • A
    7220
  • B
    7360
  • Correct answer
    C
    7260
  • D
    7380

Solution

Given,

First term of A.P are 1,2,3....10, so general term of the first term will be i

And common difference are 1,3,5,...., so general term of common difference is given by 2i-1

Now sum of the A.P  is given by,

Si=1222×i+12-12i-1

⇒Si=62×i+112i-1

⇒Si=144i-66

So, ∑i=110Si=∑i=110144i-66∑i=1101

⇒∑i=110Si=14410×112-66×10

⇒∑i=110Si=79210-66×10

⇒∑i=110Si=7260

Hence this is the correct option.

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

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