(Q26).Suppose you have Rs. 12000 to invest. You have to invest some amount at 10% and the rest at 15%. How much should be invested at each rate to yield 12% on the total amount invested ?

Let the amount to be invested @ 10% be Rs. x

and the amount to be invested @ 15% be Rs. y

By problem x + y = ……. (1)

Also 10% of x + 15% of y = 12% of 12000

⇒
100
 x +
100
 y =
100
 ×

⇒ x + y = ............(2)

equation (1) × ⇒ x + y =
equation (2)        ⇒ x + y =
-y = -
⇒ y =
-
-
 = Rs.

Substituting y = in equation (1) we get

x + = 12000

⇒ x = 12000 – =

The invested @ 10% = Rs.

@ 15% = Rs.