Question

Find the amount and the compound interest.

No.	Principal (₹)	Rate (p.c.p.a.)	Duration (Years)
1	2000	5	2
2	5000	8	3
3	4000	7.5	2

Answer 1

(1) Here, P = ₹ 2000; R = 5 %; N = 2 years

A = P`( 1 + "R"/100)^"N"`

= 2000 `(1 + 5/100)^2`

= 2000`((100+5)/100)^2`

= `2000(105/100)^2`

= `2000(105/100) xx(105/100)`

= 2000 `(21/20)^2`

= 2205 Rupees

Compound interest after 2 years,

I = Amount - Principal

 = 2205 - 2000 

= 205 Rupees

Hence, Amount =  ₹ 2205 and compound interest =  ₹205.

(2) Here, P = ₹ 5000; R = 8 %; N = 3 years

A = P `( 1 + "R"/100)^"N"`

= 5000 `(1 + 8/100)^3`

= 5000 `(108/100) xx(108/100) xx(108/100) `

= `(108 xx 108 xx54)/100`

= `629856/100`

= 6298.56 Rupees

∴ Compound interest after 3 years,

I = Amount - Principal

= 6298.56 - 5000

= 1298.56 Rupees

Hence, Amount =  ₹ 6298.56 and compound interest =  ₹1298.56

(3) Here, P = ₹ 4000; R = 7.5 % ; N = 2 years

A = P `( 1 + "R"/100)^"N"`

= 4000 `(1 + 7.5/100)^2`

= 4000 `(1 +75/1000)^2`

= 4000 `(1075/1000)xx(1075/1000)`

= `(4xx1075xx1075)/1000`

= `4622500/1000`

A = 4622.5 Rupees

∴ Compound interest after 2 years,

I = Amount - Principal

= 4622.5 - 4000

= 622.5 Rupees

Hence, Amount =  ₹ 4622.5 and compound interest =  ₹ 622.5