Given that,
The interest of sum of money is 6 yrs in 3/8 of the principal.
To find,
The rate of interest.
Solution,
Let P is the principal. It means interest will be :
I=3/8 P
The formula for the interest is given by :
[tex]I=\dfrac{PRT}{100}\\\\\dfrac{3}{8}P=\dfrac{PR\times 6}{100}\\\\\dfrac{3}{8}=\dfrac{6R}{100}\\\\R=\dfrac{300}{8\times 6}\\\\=6.25\%[/tex]
Hence, the rate of interest is 6.25%.