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14 Solving Problems Using Ratio
Basic Concepts Ratio and Percentage
When a certain amount is used as the standard, a way of expressing how
many times the standard amount is to the comparing amount by using a
fraction, decimal, and percentage is called a ratio.
When a number is expressed as a fraction of 100, it is called a percentage,
and it is expressed by using the symbol ‘%’.
Example Joe’s uncle, who runs a jewelry store, sold two rings each for $7,500.
While he made 25% profit by selling the first ring, he took a 25%
loss by selling the second ring. How much profit or loss did Joe’s
uncle make by selling the two rings?
Class Notes
The sales price of the first ring is the production cost plus % of the production cost. Let
represent the production cost. Since $7,500 0.25, then dollars.
The sales price of the second ring is the production cost minus 25% of the production cost.
Let represent the production cost. Since $7,500 0.25, then dollars.
The sum of the production costs of the two rings is $6,000 $10,000 dollars.
Since both rings were sold for $7,500 each, Joe’s uncle received a total of dollars.
Therefore, selling the two rings at this price is dollars, which is a (profit, loss) for
Joe’s uncle.
Try It Again 50% more math books were sold than English books in a
bookstore for a week. If a total of 1,000 math and English
books were sold during this period of time, how many math
books were sold?
120 NUMINO Challenge D2
Basic Concepts Ratio and Percentage
When a certain amount is used as the standard, a way of expressing how
many times the standard amount is to the comparing amount by using a
fraction, decimal, and percentage is called a ratio.
When a number is expressed as a fraction of 100, it is called a percentage,
and it is expressed by using the symbol ‘%’.
Example Joe’s uncle, who runs a jewelry store, sold two rings each for $7,500.
While he made 25% profit by selling the first ring, he took a 25%
loss by selling the second ring. How much profit or loss did Joe’s
uncle make by selling the two rings?
Class Notes
The sales price of the first ring is the production cost plus % of the production cost. Let
represent the production cost. Since $7,500 0.25, then dollars.
The sales price of the second ring is the production cost minus 25% of the production cost.
Let represent the production cost. Since $7,500 0.25, then dollars.
The sum of the production costs of the two rings is $6,000 $10,000 dollars.
Since both rings were sold for $7,500 each, Joe’s uncle received a total of dollars.
Therefore, selling the two rings at this price is dollars, which is a (profit, loss) for
Joe’s uncle.
Try It Again 50% more math books were sold than English books in a
bookstore for a week. If a total of 1,000 math and English
books were sold during this period of time, how many math
books were sold?
120 NUMINO Challenge D2
