Profit And Loss
Math MCQs

Question :    William loses 70% by selling an article for $1008.00 For how much should he sell it to get a profit of 69%?

Correct Answer  5678.4

Solution & Explanation

Strategy to solve the question

Step (1) Calculate the cost price at given loss percent and the sale price.

Step (2) After gettting the cost price find the sale price at given profit percent.

Solution

Method (1) Formula Method

Finding the Sale Price to earn a profit using formula when the Sale Price at a loss is given

Given, the sale price (SP) = $1008

And, the loss = 70%

Then, the Sale Price (SP) to earn a profit of 69% = ?

Formula to find the cost price when the sale price and loss percent are known

Cost Price (CP) = ¹⁰⁰/_{100 – gain%} × SP

Thus, the Cost Price (CP)

= ¹⁰⁰/_{100 – 70} × 1008

= ¹⁰⁰/₃₀ × 1008

= ^{100 × 1008}/₃₀

= ¹⁰⁰⁸⁰⁰/₃₀ = 3360

Thus, the Cost Price (CP) = $3360

Finding the Sale Price using the formula when the cost price and Profit percent are known

Here now, CP = $3360

And, profit = 69%

Thus Sale Price (SP) = ?

Formula to find the Sale Price (SP) when the cost price (CP) and profit percent are known

Sale Price (SP) = ^{100 + gain%}/₁₀₀ × Cost Price (CP)

Thus, the Sale Price (SP)

= ^{100 + 69}/₁₀₀ × 3360

= ¹⁶⁹/₁₀₀ × 3360

= ^{169 × 3360}/₁₀₀

= ⁵⁶⁷⁸⁴⁰/₁₀₀ = 5678.4

Thus, Sale Price (SP) at a profit of 69% = $5678.4 Answer

Method (2) Algebraic Method

Finding the Sale Price (SP) to earn the given profit using the Algebraic Method when the Sale Pric (SP) at a loss percent is given

Given, the sale price (SP) = $1008

And, the loss = 70%

Then, the Sale Price (SP) to earn a profit of 69% = ?

Let the Cost Price (CP) = m

Here given loss = 70%

Calculation of loss

loss is calculated on cost price (CP)

Formula to find the loss = loss% of CP

Thus, loss on the cost price of m

= 70% of m

= 70% × m

= ⁷⁰/₁₀₀ × m

⇒ loss = ^{70 m}/₁₀₀

Calculation of Cost Price (CP)

The Sale Price (SP) = Cost Price (CP) – loss

⇒ 1008 = m – ^{70 m}/₁₀₀

⇒ 1008 = ^{100 m – 70 m}/₁₀₀

⇒ 1008 = ^{30 m}/₁₀₀

After cross multiplication, we get

1008 × 100 = 30 m

⇒ 30 m = 1008 × 100

⇒ m = ^{1008 × 100}/₃₀

⇒ m = ¹⁰⁰⁸⁰⁰/₃₀ = 3360

⇒ m = 3360

Thus, the Cost Price (CP) = $3360

Finding the Sale Price (SP) when the Cost Price (CP) and profit percent are known

Now, here, Cost Price = 3360

And, the profit = 69%

Thus, Sale Price (SP)

= Cost Price (CP) + 69% of Cost Price (CP)

= 3360 + ⁶⁹/₁₀₀ × 3360

= 3360 + ^{69 × 3360}/₁₀₀

= 3360 + ²³¹⁸⁴⁰/₁₀₀

= 3360 + 2318.4 = 5678.4

Thus, Sale Price (SP) at a profit of 69% = $5678.4 Answer

Method (3) Unitary Method

Finding the Sale Price (SP) to earn a given profit when the Sale price (SP) at a loss is given

Given, the sale price (SP) = $1008

And, the loss = 70%

Then, the Sale Price (SP) to earn a profit of 69% = ?

Let, CP = 100

69% profit = 69% of CP

= 69% of 100 = 69

Thus, Sale Price to earn a profit of 69% = CP + 69

= 100 + 69 = 169

⇒ Sale Price to earn a profit of 69% = 169

70% loss = 70% of CP

= 70% of 100 = 70

Thus, Sale Price at a loss of 70% = CP – Loss

= 100 – 70 = 30

⇒ Sale Price at a loss of 70% = 30

∵ If the Sale Price is 30, then to earn a profit of 69% the Sale Price should be = 169

∴ If the Sale Price is 1, then to earn a profit of 69% the Sale Price should be

= ¹⁶⁹/₃₀

∴ If the Sale Price is 1008, then to earn a profit of 69% the Sale Price should be

= ¹⁶⁹/₃₀ × 1008

= ^{169 × 1008}/₃₀

= ¹⁷⁰³⁵²/₃₀ = 5678.4

Thus, Sale Price to get a profit of 69% = $5678.4 Answer

Method (4) Shortcut Method

Shortcut Method to find the Sale Price at a given profit when Sale Price at a loss is given

Given, the sale price (SP) = $1008

And, the loss = 70%

Then, the Sale Price (SP) to earn a profit of 69% = ?

Here, the Sale Price at a loss of 70 = $1008

This means 30% of the Cost Price (CP) = 1008

Therefore, 1% of the Cost Price (CP) = ¹⁰⁰⁸/₃₀

Therefore, 100% of the Cost Price (CP)

= ¹⁰⁰⁸/₃₀ × 100 = 3360

Thus, the Cost Price (CP) = $3360

Now, we need to find the Sale Price at a profit of 69%

Thus, Sale Price at a profit of 69%

= 169% of the Cost Price (CP)

= 169% of 3360

= ¹⁶⁹/₁₀₀ × 3360 = 5678.4

Thus, the Cost Price at a profit of 69% = $5678.4 Answer

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