Question

A certain sum amounts to Rs.1725 in 3 years and Rs.1875 in 5 years. Find the rate % per annum?

Answer 1

A certain sum amounts to Rs. 1725 in 3 years


and amounts to Rs.1875 in 5 years

so interest of 2 years = 1875 -1725

= 150

so interest of 1 year = 75

so interest of 3 years = 75 × 3 =225 rs

so , Principal = Amount - SI

= 1725 - 225

= 1500 rs


now ,

S.I. = P × N × R /100

75 = 1500 × 1 × R /100

R = 75 / 15

R = 5 pcpa

Answer 2

Answer:

5 %

Step-by-step explanation:

Let, p = Principle;

1st Case:

SI = (p * r * 3) / 100  = 1725 - p

   or, p * r * 3 = 172500 - 100p

   or, 3pr + 100p = 172500

   or, p = 172500/(3r + 100)

2nd Case:

SI = (p * r * 5) = 187500 - 100p

   or, 5pr + 100p = 187500

   or, p = 187500/(pr + 100)

Now, both case    p   are same

172500/(3r + 100) = 187500/(3r + 100)

or, p = 5%