The simple interest of an amount is \(\frac{16}{25}\) of the principal. Find the rate of interest per annum, if the time and interest rate both are numerically equal .

8 %

ATQ,

S.I. = \(\frac{16}{25}\) of P

Principal : S.I. = 25 : 16

Total rate of interest = \(\frac{16}{25}\) × 100% = 64%

Note: {Rate of int.(p.a.) × time = Total Rate of Interest}

Therefore,

R × T = Total Rate of Interest                                   (time = rate (given))

R² = 64

R = 8