They say the third time is a charm. November was the third month of Young Saint Louis.com's Math Puzzler contest. After having no winners the first two months, six kids answered all the November puzzlers correctly.

Those kids who gave right answers for all six November puzzlers were:

Kate Carlson of St. Louis, Ben Dickmann of St. Louis, Jackie Jones of St. Louis, Courtney Lauer of St. Louis, Gabriela Lor of Kirkwood and Rececca Stuckmeyer of St. Louis.

As we promised, we put all winning entries into a hat and drew out three who would be awarded $10 Borders gift certificates. After the random drawing, the three who won the gift certificates were:

Kate Carlson, Courtney Lauer and Jackie Jones.

Their gift certificates are in the mail to their homes.

Kate Carlson and Jackie Jones were among 13 students from St. Gabriel School who mailed all their entries together. They were all students in Teacher Amy Richardson's seventh and eighth grade math classes.

Richardson gave students in her two seventh and two eighth grade math classes a chance to work on the Puzzlers for extra credit. Then, she bundled up the completed entries into a single envelope and mailed them.

Most of the Math Puzzler entries come as individual entries. Either way is fine.

Each month, Young Saint Louis.com publishes a series of six Math Puzzlers. These are primarily to let our viewers to have fun with math concepts. These are not designed as a class assignment.

YSL.com believes the more fun you get out of math, the more you'll learn about this very important subject.

 

Answers to November, 2001, Math Puzzlers

 

1. If six boys drink 12 malteds in 90 minutes, how many malteds could four boys drink in three hours?

Answer: 16 malteds

Explanation: If six boys drink 12 malteds in 1 1/2 hours (90 minutes), that means each boy drinks two malteds in that 1 1/2 hours. Therefore, they each could drink four malteds in three hours. Four times four is 16.

 

2. What three-digit whole number can be divided evenly by 32 different whole numbers?

Answer: 840

Explanation: The 32 different whole numbers that divide evenly into 840 are: 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 15, 20, 21, 24, 28, 30, 35, 40, 42, 56, 60, 70, 84, 105, 120, 140, 168, 210, 280, 420 and 840.

 

3. Which cube can't be made from the flattened plan?

Answer: B

Explanation: The best way to solve this problem is to cut out the flattened plan, fold it into a square and compare that with the other illustrations.

 

4. Marian bought four oranges and three lemons for 90 cents on Tuesday. She bought three oranges and four lemons for 85 cents on Wednesday. What is the cost of each orange and each lemon?

Answer: 15 cents per orange;10 cents per lemon

Explanation: You can use an algebra formula to find the price of a lemon. Using Z to represent oranges and L for lemons, you get

4Z + 3L = 90 and 3Z + 4L = 85. 

3(4Z + 3L = 90) or 12Z + 9L = 270

4(3Z + 4L = 85) or 12Z + 16L = 340

subtraction leaves 0 -7L = -70

                or L = 10

Once you know the lemon price, it's easy to figure the price of an orange, 15 cents.

 

5. Bill, Alice, Dave, Ellen and Frank were in a math contest. Bill was neither first or last. Alice beat Bill. Frank was beaten by Dave. Ellen beat Dave and Frank. Bill beat Ellen. Who was first?

Answer: Alice

Explanation: Here, you just stack the names to match the relationships to each other and Alice ends up in first place.

 

6. Each different symbol represents a different number. The sum of each column and each row is shown, except for the extreme right vertical column (marked with a ?). Supply the missing number for that column.

Answer: 11

Explanation: Assign a number for each symbol and test various combinations to the vertical and horizontal totals you know. After some trial and error, you end up with the diamond equaling 4, the asterisk (*) equaling 1, the squiggle equaling 3 and the circled x equaling 2. That means the unknown right-hand vertical total is 11.