Question

a person invested some amount at the rate of 10% simple interest and some other amount at me at the rate of 12% simple interest.He received yearly interest of Rs.130 but if he had interchanged the invested amount he would have received Rs 4 more as interest.How much amount did he invest at different rates?

Answer 1

Let the amount invested Rs x at the rate of 12% and Rs. y at the rate of 10%

according to the question 

simple intrest on Rs x at 12%  + simple intrest on Rs. y at 10% = 130 

we know simple intrest = (principle ×  rate × time )/100 and apply the formula

(x × 12 ×  1)/100 + ( y ×  10 ×  1)/100 = 130

12x + 10y = 13000  ......................( equation 1)

If he interchanged the amount invested , he would have received 4 more on intrest 

then

simple intrest on Rs x at 10% + simple intrest on Rs. y at 12 % = 130 + 4

( x ×  10 ×  1)/100 + ( y ×  12 ×  1)/100 = 134 

10x + 12y = 13400  ................................( equation 2)

solving  both equation we will multiply by 12 in (equation 1) and multiply by 10 in (equation 2)

144x + 120y = 156000

100x + 120y = 134000

-  -  -  ( subtracting the equation)

44x = 22000

x = 500 

put the value of x = 500 in equation 1 

12 ×  500 + 10y = 13000

6000 +10y = 13000

10y = 13000 -6000

10y = 7000

y = 7000/10

y = 700

the amount invested at 12 % is 500 Rs and 10 % is 700

we use simple intrest formula SI = (P × R × T) /100 

and the value is x = 500 Rs 

 y = 700 Rs.

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Answer 2

Step-by-step explanation:

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