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