Question

if the compound interest on Rs.12,000 for 3 years is Rs.3972,find the rate of interest per annum​

Answer 1

Answer:

principal=12000, time=3, interest=3972, amount= 12000+3972=15972

15972=12000=[1+R/100 ]

15972=[1+R ]

12000      100

[1+R ]=15972= 1331= [11]3

    100   12000   1000     10

R   = 11-1

100   10

R=1 * 100

   10

R= 20%

Answer 2

The amount at the end of 'n' years of investing in compound interest.

$A = P(1 + \frac{r}{100} {)}^{n}$

$here,$

$P = 12000$

$n = 3$

$r = 5\%$

$A = 12000(1 + \frac{5}{100} {)}^{3}$

$= rs.13891.5$

now, compound interest

$CI = amount - principle \\ = 13891.5 - 12000 \\ \boxed{= rs.1891.5}$