When things vary directly the formula
y = kx
(y varies directly as x)
Example 1
y varies directly as x, and y = 18 when x = 3
Find the constant of variation
y varies directly as x, and y=300 when x=5.
Find y when x=15
a) Find the constant
b) Write an equation for the variation
c) Find y
The amount of interest earned on saving is directly proportional to the
amount of money saved. If $26 interest is earned on $325, how much
interest will be earned on $900 in the same period of time?
a) What is the constant
b) What is the formula for the variation
c) How much interest
An employee's wages are directly proportional to the time
worked. If an employee earns $120 for 8 hours, how much will
the employee earn for 20 hours?
a) Write a general equation for the variation
b) Find the constant
c) Write a specific equation for this situation
d) Find how much they will earn