5.3 – Direct and Partial Variation
If the equation of a line is the form y=mx, it is _______________ variation. If it is
the form y=mx+b, it is _____________ variation.
1. To fix a car, Syna’s Garage charges a flat fee of %15, plus $45/h.
a) Write an equation for graphing this situation. (It must be in the form y = mx
+ b). What does x represent? What does y represent?
b) Is this direct or partial variation? Explain.
c) Use the equation to find the cost of a repair job lasting 9.5h.
2. The-Dream, wrote Rihanna’s hit song “Umbrella”. He earns $0.091 per
copy sold, since he co-wrote the song.
a) Write the equation for graphing this situation.
b) Is this direct or partial variation? Explain.
c) Umbrella gone on to sell 17 million copies in the United States. Use the
equation to calculate the royalties The-Dream has earned.
d) The-Dream recently boasted that he has earned $15 million dollars for
writing “Umbrella”. Is this a true statement? How many copies of the song
must be sold for him to make $15 million dollars?