Question

A man invested an amount of 12% per annum simple interest and another amount at 10% per annum
simple interest. He recieved an annual interest of Rs 2600 but he had interchanged the amount invested he could have recieve
Rs 140 less. What amounts did he invest at different rates.

Answer 1

 lets call bank A giving 12% interest per annum

and  bank B giving 10% per annum

now Case 1 :

Rs. x in bank A  and Rs. y in bank B

so principal amount in bank A = Rs. x
                     rate = 12 % = 12/100
                   time = 1 year
so interest in his investment = 12x/100 = 3x/25

while in bank B
principal amount = Rs. y
rate = 10% = 10/100
time = 1 yr

so interest on his investment = 10y/100 = y/10

A/Q  =    total interest he gets =  3x/25 + y/10 = 2600

     6x + 5y =130000            ..........(1)


Case 2: 

Principal amount in bank A = Rs. y
 rate = 12%= 12/100
time = 1 yr

so simple interest = 12y/100 = 3y/25

similarly bank B princpal amount = Rs. x
rate = 10% = 10/100
time = 1 yr

so simple interest = x/10

A/Q =  total interest = 3y/25 + x/10 = 2600 - 140 = 2460

⇒  6y + 5x = 123000          .......(2)

solving 1 and 2 gives

     x= Rs 15000          and y = Rs 8000



hope my ans  is correct ............doubts, then ask?

Answer 2

Answer:

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