Question

`Find the compound interest when principa l=Rs 3000, rate =5% per annum and time =2 and half years (2 1/2) `​

Answer 1

Step-by-step explanation:

The principal,p= Rs. 3000

The rate of interest,r= 5%

Time = 2 and half years

$= 2 \frac{1}{2} years$

Let the amount be 'x'

We know that

$x = p \times (1 + \frac{r}{100} ) {}^{time \: whole} (1 + \frac{r \times time \: fraction}{100} )$

$= > x = 3000 \times (1 + \frac{5}{100} ) {}^{2} (1 + \frac{5 \times \frac{1}{2} }{100} )$

$= > x = 3000 \times (1 + \frac{1}{20} ) {}^{2} (1 + \frac{5}{200} )$

$= > x = 3000 \times ( \frac{21}{20} ) {}^{2} \times (1 + \frac{1}{40} )$

$= > x = 3000 \times \frac{21 \times 21}{20 \times 20} \times \frac{41}{40}$

$= > x = 3 \times \frac{441}{4} \times \frac{41}{4}$

$= > x = \frac{3 \times 441 \times 41}{4 \times 4}$

$= > x = \frac{54243}{16}$

$so \: \: x = 3390.19$

Therefore the required compound interest = Rs.3390.19 - Rs.3000

=Rs. 390.19