If compound interest on a certain sum for 3 years at rate of 12.5% p.a. is Rs. 151.90. Then find double of principal.

716.8

12.5% = \(\frac{1}{8}\)

For 3 years                     

             Principal   :    Amount

I                   8        :        9

II                  8        :        9

III                 8        :        9       

for 3 yrs.⇒ 512      :      729

C.Int. = 729 - 512 = 217

217R = 151.90 (given)

1R = 0.7

Principal ⇒ 512R =  512 × 0.7 = 358.4

Double of principal = 358.4 × 2 = 716.8