razao, proporçao e regra de 3 Flashcards
enem (25 cards)
What is the definition of ratio?
A ratio is a relationship between two numbers indicating how many times the first number contains the second.
True or False: A ratio can only be expressed in whole numbers.
False
What is a proportion?
A proportion is an equation that states two ratios are equal.
Fill in the blank: If a/b = c/d, then a, b, c, and d are said to be in _____.
proportion
What is the cross-multiplication method used for?
It is used to solve proportions by multiplying the means and extremes.
True or False: The rule of three can only be applied to direct proportions.
True
What is the formula for the rule of three in direct proportions?
If a/b = c/d, then d = (b * c) / a.
Multiple choice: Which of the following represents an inverse proportion? a) y = k/x b) y = kx
a) y = k/x
What is the first step in solving a rule of three problem?
Identify the known and unknown quantities.
Fill in the blank: In a direct proportion, if one quantity increases, the other _____
increases
What is the concept of direct proportion?
Direct proportion occurs when two quantities increase or decrease together.
True or False: Inverse proportions mean that as one quantity increases, the other decreases.
True
What does the term ‘k’ represent in the equation of direct proportion?
It represents the constant of proportionality.
Multiple choice: If 4 apples cost $2, how much do 10 apples cost? a) $4.50 b) $5.00 c) $3.50
b) $5.00
What is the relationship between the means and extremes in a proportion?
The product of the means equals the product of the extremes.
Fill in the blank: In a proportion, if a = 3, b = 6, c = 9, then d = _____.
18
What is the purpose of using ratios in real-life applications?
To compare quantities and determine relationships between them.
True or False: The rule of three can be used to find unknown values in both direct and inverse proportions.
False
What is the general approach to solving a rule of three problem?
Set up a proportion and solve for the unknown quantity.
Multiple choice: If 3 workers can complete a task in 12 hours, how long will it take 6 workers? a) 6 hours b) 8 hours c) 12 hours
b) 6 hours
What is an example of a direct proportion in everyday life?
The relationship between distance and time at a constant speed.
Fill in the blank: The constant of proportionality in an inverse proportion decreases as the _____ increases.
other quantity
What is the significance of understanding ratios and proportions for students preparing for the ENEM?
These concepts are crucial for solving mathematical problems and interpreting data.
True or False: Ratios can be simplified just like fractions.
True
