UPSC CDS Math Simple and Compound Interest Questions

Let the sum invested on 5%, 6%and 9% be x, y and z, respectively.
Interest on x = 10% of x
Interest on y = 12% of y
Interest on z = 18% of z
According to the question:10% of x = 12% of y = 18% of z = k
⇒x=

k

10%

,y=

k

12%

,z=

k

18%

x:y:z=

1

10

:

1

12

:

1

18

=18:15:10
∴z=

10

43

×17200
⇒z=4000