1) A four-mile bicycle trip keeps about ____ pounds of pollutants out of the air.
• 10
• 15
• 20
2) Biking burns about ____ calories per mile.
• 25
• 50
• 100
3) Bicycles could accommodate roughly ____ times as many people per hour as private cars in the same road space.
• 2
• 7
• 10
answers: 1. 15; 2. 25; 3. 10.