A sum of money amounts to 5200 Rs. in 5 years and to 5680 Rs. in 7 years at simple interest. The rate of interest per annum is :
A sum of money amounts to 5200 Rs. in 5 years and to 5680 Rs. in 7 years at simple interest. The rate of interest per annum is :
[A]3%
[B]4%
[C]5%
[D]6%
6%
P + SI for 5 years = 5200…………(I)
P + SI for 7 years = 5680…………(II)
On subtracting equation (I) from (II)
SI for 2 years = 480
∴ SI for 1 years = 240
∴ From equation (I),
P + 5 $latex \times$ 240 = 5200
$latex => P = 5200 – 1200 = 4000 Rs.$
$latex \therefore R = \frac{SI\times 100}{T\times P}&s=1$
$latex = \frac{240\times 100}{1\times 4000} = 6\%&s=1$
Hence option [D] is correct answer.