Question

In an AP of 24 terms the sum of the a₁ + a₅ + a₁₀ + a₁₅ + a₂₀ + a₂₄ = 475 Then find the sum of S₁₂.

Answer 1

Answer:

900

Step-by-step explanation:

Given,

a1+a5ta10+a15+a20+a23 = 225

at (at4d) + (a+9d) + (a+14d) + (a+19d)+

(a+22d) =225

6a+69d = 225

Here, Sn = n/2(at1)

So,

s24 24/2(at(a+23d)

12 (2a+23d)

12 (225/3)

= 4*225

900