Hands-on math!

Washington State Math Olympiad
Hints and Solutions
2016 Grade 8 Measurement
Problem
1) Markus is on his school's swim team and is working to improve his lap time. On January 31st, his average lap time was 31.23 seconds. If Markus improves his average by 10% every month, what should his average lap time be on May 31st? (Round your answer to the nearest hundredth of a second)

2) Carrie took a train that travels at 70 mph from home to work. The train she took for the return trip traveled at 90 mph. What was her average speed for the round trip?

3) If you take a cube and shrink each length by a factor of 3, what is ratio of the final volume to the initial volume?

Problem
4) Arthur and his brother Bertie together weigh 241 pounds. Arthur and his other brother Charlie together weigh 212 pounds. Bertie and Charlie together weigh 225 pounds. How much does Arthur weigh by himself?

5) Write the ratio of 62⁄5 to 4 in the lowest improper term.