Finding the final amount given the original amount and a percentage increase or decrease



In this lesson, we learn how to find a final amount, given an original amount and a percentage increase or decrease. The percentage increase may be a markup or profit or just increase in price. Similarly, the percentage decrease may be markdown or discount or loss.

Rules to find the final amount given the original amount and a percentage increase or decrease.

  • First consider the original amount.

  • Then consider the rate or percentage increase or decrease

  • To find the markup or discount, multiply the rate by the original amount.

  • To find the final amount, add or subtract the markup or discount from original amount.

The next model of a sports car will cost 6% more than the current model. The current model costs $4,000. How much will the price increase in dollars? What will be the price of the next model?

Solution

Step 1:

Current model price = $40,000

Percentage increase in price = 6%;

Step 2:

Price increase in dollars = 6% of $40,000 = 0.06 × 4000 = $2400

Next model price = current model price + increase in price

= $40,000 + $2,400

= $42,400

A store was selling lawn chairs at a unit price of $48. The store further offered a 15% markdown on the price of the chair. How much would a chair now cost?

Solution

Step 1:

Price of lawn chair = $48

Markdown = 15% of $48 = 0.15 × 48 = $7.20

Step 2:

Price after discount = $48 – $7.20 = $40.80



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