Direct Variation
y varies directly as x. If x = 5 when y = 12, find x when y = 30.
x = 12.5
Say z varies jointly as x and y. z is -32 when x is 4 and y is 1. What is z when x is 9 and y is 7?
-504
If x varies inversely as y, and x = -34 when y = -2, find the value of x when y = 4.
17
Eduardo counted ten seconds before seeing lightning and hearing thunder, and he knew that the lightning was about 2 miles away. If he counted 4 seconds between the next flash of lightning and thunder, about how far away was the lightning?
4/5 miles
This equation is classified as inverse:
c = 3v
False, it's classified as direct.
A dishwasher uses 65 gallons of water to wash 5 loads of dishes. How many gallons of water would be used to wash 12 loads?
156 gallons
Say z varies jointly as x and y. z is 4 when x is 1 and y is 2. What is z when x is 3 and y is 7?
42
If x varies inversely as y, and x = 9 when y = 8, find x when y = 12.
6
Write an equation for the following and find the value of the constant of variation.
N varies jointly as p and q. N = 72 when p = 3 and q = 2.
N = kpq and 12
This equation can be classified as direct:
m = -5p
True
At top speed, a rabbit can cover 7 miles in 12 minutes. If a rabbit could continue at this rate indefinitely, how long would it take the rabbit to cross the 220-mile expanse of the Mojave Desert?
Say z varies jointly as x and y. z is -162 when x is 9 and y is 3. What is z when x is 5 and y is 9?
-270
If x varies inversely as y and x = 12 when y = 4, what is the value of y when x = 16.
3
5
The constant of variation in this equation is 4.
d = 4t
True, k = 4
A person's weekly is directly proportional to the number of hours worked. Shawn's pay is $123 for 20 hours of work. Find the amount of pay for 31 hours of work.
$190.65
Suppose y varies jointly with x and z. If y = 20 when x = 2 and z = 5, find y when x = 14 and z = 8.
224
If x varies inversely as y and x = 8 when y = 3, find the value of x when y = 6.
4
The width of a rectangle with constant area varies inversely as its length. if the width is 4 when the length is 12, find the width when the length is 16.
3
The constant of variation for this equation is f.
n = 1/2 f
False, k = 1/2
Heather's weekly pay is directly proportional to the number of hours she works at the record store. Her pay is $174 for 24 hours of work. Find the amount of pay for 40 hours of work.
$290
Write an equation for the following:
r varies jointly as t and u.r = ktu
If P varies inversely as V, and P = 700 when V = 8, find the value of V when P = 350.
16
y varies directly with x. If y = 15 when x = -18, find y when x = 1.6.
-4/3
The formula for joint variation is y = k/x.
False, it's y = kxz.