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Answer the 3rd question.
Q.3. At a certain rate of simple interest, a sum amounts to Rs. 4760 in 3 years and Rs. 5600 in 5 years, Find the sum and the rate per cent per annum.
 

interest per annum= rs5600-rs4760/2
                             =840/2
                             =rs420
sum=rs4760-3(rs420)
       =rs4760-rs1260
       =rs3500

​3500*r*3/100=420
=42000=10500r
=r=42000/10500
=r=4%p.a