PROBLEM SOLVING WITH DIRECT VARIATION

1. The cost of lunch, c, varies directly as the number of people, n. If lunch for 3 people costs $13.50, find the cost for 6 people.

2. An empty water tank is being filled by a pump. After 2 minutes, the tank contains 125 gallons. If the volume of water in the tank varies directly as the time the water is pumped, how much water is in the tank after 5 minutes?

3. The number of students served in a cafeteria varies directly as time. If 10 students can be served in 6 minutes, how many students can be served in 48 minutes?

4. Julio’s wages vary directly as the number of hours that he works. If his wages for 5 hours are $29.75, how much will they be for 30 hours?

5. The weight of an object on the moon varies directly as its weight on Earth. With all of his gear on, Neil Armstrong weighed 360 pounds on Earth. When he became the first person to step on the moon on July 20, 1969, he weighed 60 pounds. Tara weighs 108 pounds on Earth. What would she weigh on the moon?

6. In an electrical transformer, voltage is directly proportional to the number of turns on the coil. If 110 volts comes from 55 turns, what would be the voltage produced by 66 turns?

7. If 2.5 m of copper wire weighs 0.325 kg, how much will 75 m of wire weigh?

8. Five pounds of sugar cost $2.00. At that rate, how much will 40 pounds of sugar cost?

9. A car uses 5 gallons of gasoline to travel 145 miles. At that rate, how much gasoline will the car use to travel 580 miles?

10. Ahmed’s wages vary directly as the days he works. If his wages for 5 days are $26, how much would they be for 12 days?

11. The number of bolts b a machine can make varies directly as the time it operates. It can make 6578 bolts in 2 hours. How many can it make in 5 hours?

12. The amount A which a family gives to charity varies directly as its income L. Last year, the family earned $30,000 and gave $4000 to charity. How much will they give if they make $45,000 this year?

13. A person’s paycheck P varies directly as the number of hours h worked. The pay is $165 for working 20 hours. Find the pay for 30 hours of work.