Question

What will be the compound interest on 4,000 in two years when rate of interest
is 5% per annum?​

Answer 1

✰ Question :- What will be the compound interest on 4,000 in two years when rate of interest is 5% per annum?

✫ Formula used :-

• Amount = Principal * [ 1 + (Rate/100) ]^Time
• Compound interest = Amount - Principal.

✰ Solution :-

putting all values in above formula we get,

⟼ A = 4000 * [ 1 + (5/100) ]²

⟼ A = 4000 * [ 1 + 1/20 ] ²

⟼ A = 4000 * (21/20)²

⟼ A = 4000 * 21/20 * 21/20

⟼ A = 4410

So,

⟿ CI = A - P

⟿ CI = 4410 - 4000

⟿ CI = Rs. 410

Hence, we get, Rs.410 as compound interest.

Answer 2

$\Huge{\underline{\underline{\red{\mathfrak{Answer :}}}}}$

Given :

• Principal (P) = Rs. 4000
• Time (t) = 2 yrs
• Rate of Interest (R) = 5 %

Solution :

$\large \bigstar {\boxed{\sf{Amount \: = \: Principal \bigg[ 1 \: + \: \bigg( \dfrac{Rate}{100} \bigg) \bigg]^{time}}}} \\ \\ \\ \implies {\sf{Amount \: = \: 4000 \bigg[ 1 \: + \: \bigg( \dfrac{5}{100}\bigg) \bigg]^2}} \\ \\ \\ \implies {\sf{Amount \: = \: 4000 \bigg[ 1 \: + \: \bigg( \dfrac{1}{20} \bigg) \bigg]^2 }} \\ \\ \\ \implies {\sf{Amount \: = \: 4000 \bigg( \dfrac{21}{20} \bigg)^2}} \\ \\ \\ \implies {\sf{Amount \: = \: 4000 \: \times \: \dfrac{441}{400}}} \\ \\ \\ \implies {\sf{Amount \: = \: 4000 \: \times \: 1.102}} \\ \\ \\ \implies {\sf{Amount \: = \: 4410}} \\ \\ \\ \large {\boxed{\sf{Amount \: = \: Rs. 4410}}}$

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And formula for Compound Interest is :

$\large \bigstar {\boxed{\sf{C.I \: = \: Amount \: - \: Principal}}} \\ \\ \\ \implies {\sf{C.I \: = \: 4410 \: - \: 4000}} \\ \\ \\ \implies {\sf{C.I \: = \: 410}} \\ \\ \\ \large {\boxed{\sf{Compound \: Interest \: = \: Rs. 410}}}$