Lesson 3.4 Direct Variation

The cost for electricity varies directly with the amount of kilowatt-hours of electricity used. The cost for using 1,079 kilowatt-hours of electricity was $129.48. What was the cost for using 908 kilowatt-hours of electricity?

• $41.52

• $153.86

• $75.67

• $108.96

Kenny paid $3.76 for 8 small avocados. Each small avocado costs the same amount. Which function can be used to find the total cost in dollars, c, for purchasing n avocados?

Millie weighed a substance in her science lab that was 0.00003 lbs. What is the value of the exponent when this number is written in scientific notation?

A country has a population of 42,670,000. What is the value of the exponent when this number is written in scientific notation?

The amount of fertilizer John uses varies directly with the square feet he is treating. He uses 1.5 pounds of fertilizer to treat 120 square feet. How many pounds of fertilizer would John need to treat 300 square feet?

• 4.5 pounds

• 3.75 pounds

• 80 pounds

• 24,000 pounds