Problems Involving Direct Variation

The amount of water an electric dishwasher uses to wash dishes varies directly with the number of loads of dishes. The dishwasher uses 32 gallons of water to wash 4 loads of dishes. It will take ____ gallons of water to wash 10 loads of dishes.

The cost of buying apples for the Fall Festival varies directly with the number of bags purchased. It will cost $___ to purchase 7 bags.

The total profit from the Band's spaghetti dinner fundraiser varies directly with the number of dinner tickets sold. If the sale of 22 tickets results in $253 profit, how many tickets must be sold to reach the fundraising goal of $700?

• 21 tickets

• 55 tickets

• 61 tickets

• 46 tickets

The cost of a pizza varies directly with the length of the diameter of the pizza. If a pizza with a 12-inch diameter costs $8.64, a pizza with a 16-inch diamter should cost $_______.

n varies directly with c. If c = 24 when n = 18, what is c when n = 22?

• 88/3

• 28

• 66/4

• 24

Y varies directly as x. If y = 12 when x = 15, what is y when x = 20?

• 4/5

• 17

• 16

• 25

When swimming underwater, ear pressure varies directly with depth. The pressure in the ears is 8.6 pounds per square inch as a depth of 20 feet. What is the pressure, in pounds per square inch, at a depth of 40 feet?

• 93 lb/sq in

• 46.5 lb/sq in

• 33.8 lb/sq in

• 17.2 lb/sq in

The distance a car travels varies directly with time. If the car travels 100 miles in 2 hours, how far will it travel in 5 hours?

• 200 miles

• 250 miles

• 400 miles

• 50 0miles

The stretch of a spring varies directly with the weight attached to it. If the spring stretches 3 cm when a 5 kg weight is attached, how far will the spring stretch if a 20 kg weight is attached, assuming the spring obeys Hooke's law?

• 4 cm

• 5 cm

• 12 cm

• 60 cm