Ratios Rule!
What is a ratio?
A comparison of two quantities
What point must every proportional graph go through?
(0,0)
What is the constant of proportionality in y = 3x?
3
A car travels 60 miles in 2 hours. What’s the unit rate?
30mph
What’s the equation for a proportional relationship?
y=kx
Write the ratio 3 to 5 as a fraction.
3/5
True or False: Every straight line shows a proportional relationship.
False; It must go through the origin
In y = 5x, what happens to y when x doubles?
y doubles
A recipe uses 2 cups of sugar for 5 cups of flour. What’s the rate of sugar per cup of flour?
The rate is 0.4 cups of sugar per cup of flour
What is y when x = 4 and k = 2?
8
The ratio of cats to dogs is 2:3. If there are 8 cats, how many dogs?
12 Dogs
What does constant of proportionality represent in a equation?
K
If y = 12 when x = 4, what’s k?
k=3
You earn $24 for 3 hours. How much for 8 hours?
64
If y = 3x, what is x when y = 12?
4
Simplify 12:18.
2:3
Identify the constant of proportionality from a graph that passes through (2, 10).
5
A table shows y = 9 when x = 3 and y = 15 when x = 5 — what’s k?
k=3
6 notebooks cost $9. Find the cost per notebook.
Each notebook cost 1.5.
Fill in the blank: If y/x = k, then y = ______.
kx
If 4 pencils cost $2, what’s the cost for 10 pencils?
$5
How do you know from a table that a relationship is proportional?
If you can find the constant
It took Megan 4 minutes to drink 3 ounces of water. What is the meaning of the situation? Hint: Find K
A runner travels 4 miles in 32 minutes. What’s the pace (minutes per mile)?
Eight minutes per hour
He can buy 5 Tickets