Problems Involving Direct Variation

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 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 $_______.

Does the equation y = 2.3x + 4 show a direct variation? Explain why or why not.

• Yes, the constant of variation is 2.3.

• No, the constant of variation has to be expressed as a whole number or a fraction.

• Yes, this is a proportional relationship.

• No, the graph of this equation does not pass through the origin.