Given, n = 2 yr, R = 4% and SI = 80
According to the formula,
CI = SI(1 + 4/200)

Correct Option: B

Given, n = 2 yr, R = 4% and SI = 80
According to the formula,
CI = SI(1 + 4/200) = 80 x 51/50 = ₹ 81.60

Given, P = ₹ 4000
R₁= 10% (decreased), R₂ = 5% (decreases) and R₃ = 15% (growth)
∴ According to the formula,
Income at the end of third year = P(1 - R₁/100)(1 - R₂/100)(1 + R₃/100)
= 4000(1- 10/100) (1 - 5/100) (1 + 15/100)

Correct Option: A

Given, P = ₹ 4000
R₁= 10% (decreased), R₂ = 5% (decreases) and R₃ = 15% (growth)
∴ According to the formula,
Income at the end of third year = P(1 - R₁/100)(1 - R₂/100)(1 + R₃/100)
= 4000(1- 10/100) (1 - 5/100) (1 + 15/100)
= 4000 x (9/10) x (19/20) x (23/20)
= 9 x 19 x 23
= ₹ 3933

Given, P =₹ 4000,
n = 9 months = 3/4 yr and
CI = ₹ 630.50
Amount = P + CI = 4000 + 630.50 = ₹ 4630.50

According to the formula,
⇒ Amount = P[(1+R/(100 x 4)]⁴ⁿ
⇒ 4630.50 = 4000(1+R/400)^{4 x 3/4}

Correct Option: A

Given, P =₹ 4000,
n = 9 months = 3/4 yr and
CI = ₹ 630.50
Amount = P + CI = 4000 + 630.50 = ₹ 4630.50

According to the formula,
⇒ Amount = P[(1+R/(100 x 4)]⁴ⁿ
⇒ 4630.50 = 4000(1+R/400)^{4 x 3/4}
⇒ 4630.50 = 4000[(400 + R)/400]³
⇒ 4630.50/4000 = [(400 + R)/400]³
⇒ 9261/8000 = [(400 + R)/400]³
⇒ (21/20)³ = [(400 + R)/400]³
⇒ [(400 + R)/400]/400 = 21/20
⇒ 400 + R = 21 x 20 = 420
∴ R = 420 - 400 = 20%

Let the sum be ₹ P .
Then, CI when compounded half - yearly = [P x (1 + 10/100)⁴ - P] = 4641P/10000
CI when compounded annually = [ P x (1 + 20/100)² - P] = 11P/25
According to the question, 4641P/10000 - 11P/25 = 964
⇒ [(4641 - 4400)/10000] x P = 964

Correct Option: A

Let the sum be ₹ P .
Then, CI when compounded half - yearly = [P x (1 + 10/100)⁴ - P] = 4641P/10000
CI when compounded annually = [ P x (1 + 20/100)² - P] = 11P/25
According to the question, 4641P/10000 - 11P/25 = 964
⇒ [(4641 - 4400)/10000] x P = 964
∴ P = (964 x 10000)/241
= ₹ 40000

According to the question,
1728 = 1331(1 + R/100)³
1728/1331 = (1 + R/100)³
⇒ (12/11)³ = (1 + R/100)³

Correct Option: B

According to the question,
1728 = 1331(1 + R/100)³
1728/1331 = (1 + R/100)³
⇒ (12/11)³ = (1 + R/100)³
⇒ 1 + R/100 = 12/11
⇒ R/100 = (12/11) - 1 = 1/11
∴ R = 100/11= 9.09%