San Diego Middle School Math Field Day 2009
DYNAMIC DUO - Part 2
1)Two digital clocks are set correctly at 12:00 pm. One watch gains 5 minute every hour. The other watch loses 10 minutes every hour. How many hours will it be when they both read the same again?
2)Katie has $0.85 worth of coins. If she has only quarters, dimes, and nickels, how many different combinations of change can she have?
3)A palindrome is a number that reads the same from left to right as it does from right to left. For example 1991 is a palindrome. How many years will it be until the next palindrome year occurs?
4)All horizontal and vertical lines of this grid have the same sum after just two numbers are interchanged. What are the numbers?
21 / 9 / 717 / 11 / 14
4 / 12 / 16
5)The cost of a certain text messaging plan is $7.99 per month plus 3¢ per text message that you send. If you are able to spend $25 per month, then how many text messages can you send per month?
6)Alvin takes all of his clean socks and dumps them into his sock drawer. He has 9 black socks, 5 red socks, and 12 white socks. How many socks does he have to draw before he is guaranteed to have a pair of the same color?
7)Karen is three times as old as Lori. Eight years from now, she will be twice as old. How old is Lori now?
8)A farmer raises chickens and cows, but doesn't know exactly how many of each type of animal he has. If he knows there are 80 heads and 220 total feet, then how many cows does he have?
9)A rectangular chalkboard is twice as long as it is wide. If the length were four feet shorter and the width were four feet wider, it would be a square. What is the length of the chalkboard?
10)If a pizza that is 8 inches in diameter costs $6, then how much should a pizza with a 16 inch diameter cost?
11)Susan woke up and realized that the time that had passed since midnight was exactly half the time it would be before the next midnight. What time did she wake up?
12)Chip said to Dale, “If you give me one acorn then we will have an equal number of acorns.” Dale replied, “ But if you give me three acorns, then I will have three times the number you have.” How many acorns did Chip have?
13)A large piece of construction paper is 0.01 in thick. It is folded over and over. What is the least number of folds it will take to be at least 1 in thick?
14)A special dartboard has equal-sized sectors with the following point values: 2, 3, 5, 7. If each person gets to throw three darts, then how many different total scores can you get?
15)Two trains 240 miles apart are traveling towards each other along the same track. The first train goes 50 miles per hour. The second train goes 70 miles per hour. A fly is hovering above the nose of the first train. It buzzes from the first train to the second train, turns around immediately, flies back to the first train, and turns around again. It goes on flying back and forth until the trains collide. If the fly’s speed is 25 miles per hour, how many miles will it travel?
16) Stan has 23 coins. He adds up their value and finds that he has $4.85. If he has just quarters and dines, how many quarters does he have?
17)Twenty ounces of lemonade that contains 80% real lemon juice is mixed with 50 ounces of another lemonade that is 50% real lemon juice. What percent of the mixture is real lemon juice? Round your answer to the nearest whole percent.
18) Spider Man and Wolverine have a race. Spider Man, thinking that he is a bit faster than Wolverine, gives Wolverine a 10-minute head start. Wolverine runs at a rate of 11 mph and Spider Man can run at 12 mph. If they happen to cross the finish line at the same time, what was the distance of the race?
19)Frank and Al are given a job to paint a house. Frank can finish the job in 3 days if he works alone, and Al could do the same job in 6 days if he works alone. How long would it take if they worked together?
20) A tree cracks 5 feet up from its base. Though still attached to the trunk, the upper part falls over until the very tip touches the ground. If the tip of the tree touches the ground exactly 12 feet from the trunk, how tall was the tree originally?
San Diego Middle School Math Field Day 2009
DYNAMIC DUO - Part 2
NAMES ______
SCHOOL ______
19.20.
For grading room use only:
Scores:
San Diego Middle School Math Field Day 2009
DYNAMIC DUO - Part 2
Answer Key
1. 48 / 19. 22. 22 / 20. 18 feet
3. 103
4. 12 and 17
5. 567
6. 4
7. 8
8. 30
9. 16
10. $24
11. 8 a.m.
12. 7
13. 7
14. 14
15. 50
16. 17
17. 59
18. 22 miles