Question:
John gets a 20% profit after selling his laptop for $372. What was the cost price of the laptop?
Correct Answer
310
Solution And Explanation
Solution
Finding the cost price if the sale price and profit percent are known
The cost price (CP) can be found using the formula, algebraic method, using shortcut method, and taking the cost price as 100, 200, 300, 400, 500, or whatever you want.
Finding the cost price using the formula when the sale price and profit percent are known
Given, the sale price (SP) = $372
And, the profit = 20%
Then, the Cost Price (CP) = ?
Formula to find the cost price when the sale price and profit percent are known
Cost Price (CP) = 100/100 + gain% × SP
Thus, the Cost Price (CP)
= 100/100 + 20 × 372
= 100 × 372/120
= 37200/120 = 310
Thus, the Cost Price (CP) = $310 Answer
Finding the cost price (CP) using the Algebraic Method when the Sale Pric (SP) and the profit percent are given
Let the Cost Price (CP) = m
Here given profit = 20%
Calculation of Profit
Profit is calculated on cost price (CP)
Formula to find the Profit = Profit% of CP
Thus, profit on the cost price of m
= 20% of m
= 20% × m
= 20/100 × m
⇒ Profit = 20 m/100
Calculation of Cost Price (CP)
The Sale Price (SP) = Cost Price (CP) + Profit
⇒ 372 = m + 20 m/100
⇒ 372 = 100 m + 20 m/100
⇒ 372 = 120 m/100
After cross multiplication, we get
372 × 100 = 120 m
⇒ 120 m = 372 × 100
⇒ m = 372 × 100/120
⇒ m = 37200/120 = 310
⇒ m = 310
Thus, the Cost Price (CP) = $310 Answer
Finding the cost price (CP) using Unitary Method by taking the cost price (CP) is equal to 100 when the SP and the profit percent are given
Given, the sale price (SP) = $372
And, the profit = 20%
Then, the Cost Price (CP) = ?
Let Cost Price (CP) = 100
Thus profit = 20% of 100 = 20
Thus, Sale Price (SP) = Cost Price (CP) + Profit
⇒ Sale Price (SP) = 100 + 20
⇒ Sale Price (SP) = 120
∵ If the Sale Price (SP) is 120, then the Cost Price (CP) = 100
∴ If the Sale Price (SP) is 1, then the Cost Price (CP)
= 100/120
∴ If the Sale Price (SP) is 372, then the Cost Price (CP)
= 100/120 × 372
= 100 × 372/120
= 37200/120 = 310
Thus, the Cost Price (CP) = $310 Answer
Shortcut Method to find Cost Price (CP) when SP and profit percent are known
Given, the sale price (SP) = $372
And, the profit = 20%
Then, the Cost Price (CP) = ?
SP = 120% of CP
⇒ SP = 120/100 × CP
⇒ 372 = 120 CP/100
After cross multiplication
⇒ 372 × 100 = 120 CP
⇒ 120 CP = 372 × 100
⇒ CP = 372 × 100/120
⇒ CP = 37200/120 = 310
⇒ CP = $310 Answer
Similar Questions
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(3) Find the profit percent if Mrs. Julie buys 29 bananas for $1 and sells 28 bananas for $1.
(4) If a hawker bought 22 apples per $1 and sold them at a rate of 21 apples per $1, then what would his profit percent be?
(5) Mr. John earns a profit of 190% by selling a old car for $10759. For how much had he purchased that house?
(6) A shopkeeper earns 130% after selling some old bikes for $5773. What was his cost price?
(7) Find the cost price, if a broker earns a profit of 370% by selling an old house for $34357
(8) Find the cost price, if a trader gets a loss of 47% by selling 500 kg rice for $4881.30
(9) Mrs. John earned a profit of 330% by selling her car. If she sold her car for $27993, then find the cost price of the car.
(10) Mr. Peter earns a profit of 110% by selling goods for $4431.00. For how much was he purchased those goods?