Here, r = 30% and r₁ = 10%
∴ Profit per cent = [{r x (100 - r₁)}/100] - r₁
= [30 x (100 - 10)/100] - 10

Correct Option: D

Here, r = 30% and r₁ = 10%
∴ Profit per cent = [{r x (100 - r₁)}/100] - r₁
= [30 x (100 - 10)/100] - 10
= [30 x 90/100] - 10
= 27 -10 = 17%

Here, r = 15% and R = 19%
∴ Requirement percentage = [(r + R) / (100 - r)] x 100%

Correct Option: B

Here, r = 15% and R = 19%
∴ Requirement percentage = [(r + R) / (100 - r)] x 100%
= [(15 + 19) / (100 - 15)] x 100% = [(34 x 100) / 85 ] % = 40%

∵ MP of the article = ₹ 60
SP of the article = [60 x (100 - 15)]/100
= (60 x 85)/100 = ₹ 51

Thus, actual SP of the article = (51 - 3) = ₹ 48
Hence, CP of the article = (48 x 100)/(100 + 20)

Correct Option: C

∵ MP of the article = ₹ 60
SP of the article = [60 x (100 - 15)]/100
= (60 x 85)/100 = ₹ 51

Thus, actual SP of the article = (51 - 3) = ₹ 48
Hence, CP of the article = (48 x 100)/(100 + 20)
= (48 x 100)/120
= ₹ 40

Here, r = 16% and R = 5%
∴ Required percentage
= [(r + R)/(100 - r)] x 100%

Correct Option: D

Here, r = 16% and R = 5%
∴ Required percentage
= [(r + R)/(100 - r)] x 100%
= [(16 + 5)/(100 - 16)] x 100% = 21 x 100/84% = 25 %

Given, r₁ = 5 %, r₂ = 6 %and earning = ₹ 15
Let marked price of the watch be ₹ N .
Then, (6 - 5) % of N = 15

Correct Option: C

Given, r₁ = 5 %, r₂ = 6 %and earning = ₹ 15
Let marked price of the watch be ₹ N .
Then, (6 - 5) % of N = 15
⇒ N = 15 x 100
∴ N = ₹ 1500