A sum amounts to ₹ 2916 in 2 yr and ₹ 3149.28 in 3 yr at compound interest. The sum is?

Let required amount be ₹ P.
According to the question,
2916 = P (1 + R/100)² ... (i)
and 3149.28 = P(1 + R/100)³ ... (ii)
On dividing Eq. (ii) by Eq. (i), we get
1 + R/100 = 3149.28/2916
⇒ R/100 = (3149.28/2916) - 1
⇒ R = (233.28/2916) x 100 = 8%
From Eq. (i),
P = (2916 x 100 x 100)/(108 x 108)
= ₹ 2500