A sum of money amounts to Rs.49400 in 3 years and Rs.50400 in 5 years at the same rate of simple interest. Find rate of interest per annum.
This question was asked in Railway Exam. Source: question number 25 in http://indread.com/wp-content/uploads/2016/01/rrc_englishpaper_8-12-2013-2.pdf
But the answer given is 8%. I think it is wrong.
My Approach $$ P(1+3R/100)=49400 \\ P(1+5R/100)=50400 $$ Solving these 2 gives answer near to 1%.
Is it correct
Yes, you are correct. I get the same with my calculation.
Simple interest amount over the $2$ year period is
$SI_2 = 50400- 49400 = 1000$
Simple interest for $5$ years is then
$SI_5 = 5*\frac{1000}{2} = 2500$
Principal amount is then
$P = 50400 - 2500 = 47900$
And the rate $I$ of interest per annum:
$I = (SI \times 100)/(P \times T)$
$I = (2500 \times 100)/(47900 \times 5) \approx 1\%$