Write the following proportion using colons: 7 is to 21 as 3 is to 9.
a) [tex]$7: 21=3: 9$[/tex]
b) [tex]$7: 3=21: 9$[/tex]
c) [tex]$21: 7=3: 9$[/tex]
d) [tex]$7: 21=9: 3$[/tex]
Answer (2)
Express the ratio '7 is to 21' as 7:21.
Express the ratio '3 is to 9' as 3:9.
Write the proportion as 7:21 = 3:9.
The correct option is 7 : 21 = 3 : 9 .
Explanation
Understanding the Proportion We are asked to express the proportion '7 is to 21 as 3 is to 9' using colons. A proportion states that two ratios are equal. The ratio '7 is to 21' can be written as 7:21, and the ratio '3 is to 9' can be written as 3:9. The proportion '7 is to 21 as 3 is to 9' can be written as 7:21 = 3:9.
Comparing with Options Now, we compare the proportion we wrote (7:21 = 3:9) with the given options: a) 7 : 21 = 3 : 9 b) 7 : 3 = 21 : 9 c) 21 : 7 = 3 : 9 d) 7 : 21 = 9 : 3 Option a) matches our proportion exactly.
Final Answer Therefore, the correct answer is a) 7 : 21 = 3 : 9 .
Examples
Proportions are used in everyday life to scale recipes, convert currencies, and understand map scales. For example, if a recipe calls for 2 cups of flour for every 1 cup of sugar, the proportion is 2:1. If you want to double the recipe, you would use 4 cups of flour for every 2 cups of sugar, maintaining the same proportion. Understanding proportions helps in making accurate adjustments and comparisons in various real-world scenarios.
The proportion '7 is to 21 as 3 is to 9' can be expressed as 7 : 21 = 3 : 9 . The correct answer from the choices given is option a) 7 : 21 = 3 : 9 . This representation shows that the two ratios are equal.
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