Question

Answer this question fast

Answer 1

Let P be the principal and R be the rate of interest.

We know that A = P(1 + r/100)^n.   -------------------------(*)

Now, Compound Interest Earned at the end of 2 years :

Given A = 8820, n = 2 years.

Substitute in (*), we get

8820 = P(1 + r/100)^2

8820 = P(100 + r/100)^2  --------------------- (1)


Now, Compound Interest Earned at the end of 3 years:

Given A = 9261,n = 3 years.

Substitute in (*), we get

9261 = P(1 + r/100)^3

9261 = P(100 + r/100)^3   ---------------------- (2)



On solving (1) & (2), we get

(100 + r/100) = 9261/8820

100 + r/100 = 1.05

100 + r = 1.05 * 100

100 + r = 105

r = 105 - 100

r = 5%.

Therefore the rate of interest = 5%.

Substitute r = 5 in (2), we get

9261 = P(1 + 5/100)^3

9261 = P(105/100)^3

9261 = P(21/20)^3

9261 = P(9261/8000)

P = 8000.

Therefore the principal = 8000.


Hope this helps!

Answer 2

Let the rate of interest is r and principal is P .
use the formula,
A = P(1 + r/100)ⁿ

A/C to question,
8820 = P(1 + r/100)² -------(1)
9261 = P(1 + r/100)³ ---------(2)

divide equation (2) by (1)
9261/8820 = (1 + r/100)
9261/8820 -1 = r/100
(9261-8820)/8820 = r/100
441/8820= 1/20 = r/100
r = 100/20 = 5%

now, put r = 5% in equation (1)
8820 = P(1 + 5/100)²
8820 = P(1.05)²
P = 8820/(1.05)² =8000

hence, P =8000 Rs