Hands-on math!

Washington State Math Olympiad
Hints and Solutions
2013 Grade 7 Algebra
Problem
1) Billy wants to purchase a new bike which costs $185. Billy mows lawns in his neighborhood to earn money. For each lawn Billy mows he makes $10. After every 3 lawns he mows, Billy must refill his mower's gas tank. It costs $8.50 to refill the tank. How many whole lawns will Billy have to mow to make enough money to buy the new bike?

2) Consider the sequence of triangles shown. If the patterns in the side lengths continue, what is the area of the 5th triangle in the sequence in square units?

Problem

3) Marie lives 5 miles from school and bikes at an easy rate of 6 miles per hour. Her sister Kate takes the same route but is a bike racer. She rides at a rate of 25 miles per hour. If they arrive at school at the same time, how many minutes earlier than Kate does Marie need to leave?

4) Consider the sequence of figures made up of little squares shown. Divide the total number of little squares in Figure 10 by 11. What is that quotient?

5) Molly's Limo service provides the graphic below to display its airport service prices. I live 20 miles from the airport. What will it cost me if I use this service?