48.David Ruppel sold his house for $159,000. He got this amount knowing that he would have
to pay a 6% commission to his agent. What amount did he have after the agent was paid?
Solve each investment problem. See Example 6.
78 CHAPTER 2 Linear Equations, Inequalities, and Applications
49.Mario Toussaint earned $12,000 last
year by giving tennis lessons. He in-
vested part of the money at 3% simple
interest and the rest at 4%. In one year,
he earned a total of $440 in interest.
How much did he invest at each rate?
50.Sheryl Zavertnik won $60,000 on a slot
machine in Las Vegas. She invested part
of the money at 2% simple interest and
the rest at 3%. In one year, she earned a
total of $1600 in interest. How much
was invested at each rate?
Rate
Principal (as a decimal) Interest
x 0.03
0.04
Rate
Principal (as a decimal) Interest
x 0.02
51.Jennifer Siegel invested some money at 4.5% simple interest and $1000 less than twice
this amount at 3%. Her total annual income from the interest was $1020. How much was
invested at each rate?
52.Piotr Galkowski invested some money at 3.5% simple interest, and $5000 more than three
times this amount at 4%. He earned $1440 in annual interest. How much did he invest at
each rate?
53.Dan Abbey has invested $12,000 in bonds paying 6%. How much additional money
should he invest in a certificate of deposit paying 3% simple interest so that the total re-
turn on the two investments will be 4%?
54.Mona Galland received a year-end bonus of $17,000 from her company and invested the
money in an account paying 6.5%. How much additional money should she deposit in an
account paying 5% so that the return on the two investments will be 6%?
Solve each problem involving rates of concentration and mixtures. See Examples 7 and 8.
55.Ten liters of a 4% acid solution must
be mixed with a 10% solution to get a
6% solution. How many liters of the
10% solution are needed?
56.How many liters of a 14% alcohol solu-
tion must be mixed with 20 L of a
50% solution to get a 30% solution?
Liters Percent Liters of
of Solution (as a decimal) Pure Acid
10 0.04
x 0.10
0.06
Liters Percent Liters of
of Solution (as a decimal) Pure Alcohol
x 0.14
0.50
57.In a chemistry class, 12 L of a 12% alcohol solution must
be mixed with a 20% solution to get a 14% solution. How
many liters of the 20% solution are needed?
58.How many liters of a 10% alcohol solution must be mixed
with 40 L of a 50% solution to get a 40% solution?
59.How much pure dye must be added to 4 gal of a 25% dye
solution to increase the solution to 40%? (Hint:Pure dye
is 100% dye.)
60.How much water must be added to 6 gal of a 4% insecti-
cide solution to reduce the concentration to 3%? (Hint:
Water is 0% insecticide.)
