43. The simple interest on a certai...
Question
Fullscreen

43. The simple interest on a certain sum of money invested at a certain rate for 2 yr amounts to * 1200. The compound interest on the same sum of money invested at the same rate of interest for 2 yr amounts to 1290. What was the principal? RRB NTPC (Phase-1) 2016 (1) * 12000 (2) * 16000 (3) 6000 (4) * 4000

11th - 12th Class
Maths
Solution
162
Rating
4.0 (1 ratings)
Fullscreen
43. (4) Let the rate of interest be ( r % ) and amount is ( ₹ x ) According to the question. [ begin{aligned} therefore & & D_{2} &=xleft(frac{r}{100}right)^{2} Rightarrow & 1290-1200 &=frac{x times r}{100 times 100} times r Rightarrow & 90 &=frac{x times r times r}{100 times 100} 1200 &=frac{x times r times 2}{100} & 1000 end{aligned} ] Now, from Eq. (i) [ 90=frac{60000 times r}{100 times 100} Rightarrow r=15 % ] From Eq. (ii), ( 15 times x=60000 ) ( therefore quad x=₹ 4000 )
Quick and Stepwise Solutions Just click and Send Download App OVER 20 LAKH QUESTIONS ANSWERED Download App for Free