Question : Mr. Oliver loses 79% by selling an article for $800.10. For how much should he sell it to get a profit of 78%?
Correct Answer 6781.8
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) = $800.1
And, the loss = 79%
Then, the Sale Price (SP) to earn a profit of 78% = ?
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 – 79 × 800.1
= 100/21 × 800.1
= 100 × 800.1/21
= 80010/21 = 3810
Thus, the Cost Price (CP) = $3810
Finding the Sale Price using the formula when the cost price and Profit percent are known
Here now, CP = $3810
And, profit = 78%
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 + 78/100 × 3810
= 178/100 × 3810
= 178 × 3810/100
= 678180/100 = 6781.8
Thus, Sale Price (SP) at a profit of 78% = $6781.8 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) = $800.1
And, the loss = 79%
Then, the Sale Price (SP) to earn a profit of 78% = ?
Let the Cost Price (CP) = m
Here given loss = 79%
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
= 79% of m
= 79% × m
= 79/100 × m
⇒ loss = 79 m/100
Calculation of Cost Price (CP)
The Sale Price (SP) = Cost Price (CP) – loss
⇒ 800.1 = m – 79 m/100
⇒ 800.1 = 100 m – 79 m/100
⇒ 800.1 = 21 m/100
After cross multiplication, we get
800.1 × 100 = 21 m
⇒ 21 m = 800.1 × 100
⇒ m = 800.1 × 100/21
⇒ m = 80010/21 = 3810
⇒ m = 3810
Thus, the Cost Price (CP) = $3810
Finding the Sale Price (SP) when the Cost Price (CP) and profit percent are known
Now, here, Cost Price = 3810
And, the profit = 78%
Thus, Sale Price (SP)
= Cost Price (CP) + 78% of Cost Price (CP)
= 3810 + 78/100 × 3810
= 3810 + 78 × 3810/100
= 3810 + 297180/100
= 3810 + 2971.8 = 6781.8
Thus, Sale Price (SP) at a profit of 78% = $6781.8 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) = $800.1
And, the loss = 79%
Then, the Sale Price (SP) to earn a profit of 78% = ?
Let, CP = 100
78% profit = 78% of CP
= 78% of 100 = 78
Thus, Sale Price to earn a profit of 78% = CP + 78
= 100 + 78 = 178
⇒ Sale Price to earn a profit of 78% = 178
79% loss = 79% of CP
= 79% of 100 = 79
Thus, Sale Price at a loss of 79% = CP – Loss
= 100 – 79 = 21
⇒ Sale Price at a loss of 79% = 21
∵ If the Sale Price is 21, then to earn a profit of 78% the Sale Price should be = 178
∴ If the Sale Price is 1, then to earn a profit of 78% the Sale Price should be
= 178/21
∴ If the Sale Price is 800.1, then to earn a profit of 78% the Sale Price should be
= 178/21 × 800.1
= 178 × 800.1/21
= 142417.8/21 = 6781.8
Thus, Sale Price to get a profit of 78% = $6781.8 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) = $800.1
And, the loss = 79%
Then, the Sale Price (SP) to earn a profit of 78% = ?
Here, the Sale Price at a loss of 79 = $800.1
This means 21% of the Cost Price (CP) = 800.1
Therefore, 1% of the Cost Price (CP) = 800.1/21
Therefore, 100% of the Cost Price (CP)
= 800.1/21 × 100 = 3810
Thus, the Cost Price (CP) = $3810
Now, we need to find the Sale Price at a profit of 78%
Thus, Sale Price at a profit of 78%
= 178% of the Cost Price (CP)
= 178% of 3810
= 178/100 × 3810 = 6781.8
Thus, the Cost Price at a profit of 78% = $6781.8 Answer
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