## Wednesday, December 24, 2008

### December 24, 2008

A 3 x 3 x 3 cube is formed by gluing together 27 standard cubical dice. (On a standard die, the sum of the numbers on any pair of opposite faces is 7.) The smallest possible sum of all the numbers showing on the surface of the 3 x 3 x 3 cube is?

## Tuesday, December 23, 2008

### December 23, 2008

Tyler has entered a buffet line in which he chooses one kind of meat, two different vegetables and one dessert. If the order of food items is not important, how many different meals might he choose?

Interactive version of problem and solution.

*Meat: beef, chicken, pork*

Vegetables: baked beans, corn, potatoes, tomatoes

Dessert: brownies, chocolate cake, chocolate pudding, ice creamVegetables: baked beans, corn, potatoes, tomatoes

Dessert: brownies, chocolate cake, chocolate pudding, ice cream

Interactive version of problem and solution.

## Monday, December 22, 2008

### December 22, 2008

## Friday, December 19, 2008

### December 19, 2008

Yan is somewhere between his home and the stadium. To get to the stadium he can walk directly to the stadium, or else he can walk home and then ride his bicycle to the stadium. He rides 7 times as fast as he walks, and both choices require the same amount of time. What is the ratio of Yan's distance from his home to his distance from the stadium?

Interactive version of problem and solution.

Interactive version of problem and solution.

## Thursday, December 18, 2008

### December 18, 2008

A faulty car odometer proceeds from digit 3 to digit 5 , always skipping the digit 4, regardless of position. For example, after traveling one mile the odometer changed from 000039 to 000050. If the odometer now reads 002005, how many miles has the car actually traveled?

Interactive version of problem and solution.

Interactive version of problem and solution.

## Wednesday, December 17, 2008

### December 17, 2008

Let

Interactive version of problem and solution.

*f*be a linear function for which*f*(6) –*f*(2) = 12. What is*f*(12) –*f*(2)?Interactive version of problem and solution.

Buy *Hexaflexagons, Probability Paradoxes, and the Tower of Hanoi*

## Tuesday, December 16, 2008

### December 16, 2008

There are 24 four-digit whole numbers that use each of the four digits 2, 4, 5 and 7 exactly once. Only one of these four-digit numbers is a multiple of another one. Which one is it?

## Monday, December 15, 2008

### December 15, 2008

Joe had walked half way from home to school when he realized he was late. He ran the rest of the way to school. He ran 3 times as fast as he walked. Joe took 6 minutes to walk half way to school. How many minutes did it take Joe to get from home to school?

Interactive version of problem and solution.

Interactive version of problem and solution.

## Friday, December 12, 2008

### December 12, 2008

The sum of 18 consecutive positive integers is a perfect square. The smallest possible value of this sum is what?

## Thursday, December 11, 2008

### December 11, 2008

Call a set of integers

*spacy*if it contains no more than one out of any three consecutive integers. How many subsets of {1, 2, 3, . . . ,12}, including the empty set, are spacy?## Wednesday, December 10, 2008

### December 10, 2008

Six distinct positive integers are randomly chosen between 1 and 2006, inclusive. What is the probability that some pair of these integers has a difference that is a multiple of 5?

Interactive version of problem and solution.

Interactive version of problem and solution.

## Tuesday, December 9, 2008

### December 9, 2008

The equations 2

*x*+7 = 3 and*bx*– 10 = -2 have the same solution. What is the value of*b*?## Monday, December 8, 2008

## Friday, December 5, 2008

### December 5, 2008

Call a number "prime-looking" if it is composite but not divisible by 2,3, or 5. The three smallest prime-looking numbers are 49, 77, and 91. There are 168 prime numbers less than 1000. How many prime-looking numbers are there less than 1000?

## Thursday, December 4, 2008

### December 4, 2008

Sally has five red cards numbered 1 through 5 and four blue cards numbered 3 through 6. She stacks the cards so that the colors alternate and so that the number on each red card divides evenly into the number on each neighboring blue card. What is the sum of the numbers on the middle three cards?

Interactive version of problem and solution.

Interactive version of problem and solution.

## Wednesday, December 3, 2008

### December 3, 2008

A set of 25 square blocks is arranged into a 5 x 5 square. How many different combinations of 3 blocks can be selected from that set so that no two are in the same row or column?

## Tuesday, December 2, 2008

### December 2, 2008

Let

Interactive version of problem and solution.

*a,**b*, and*c*be real numbers such that*a*– 7*b*+ 8*c*= 4 and 8*a*+ 4*b*–*c*= 7. Then*a*^{2}–*b*^{2}+*c*^{2}is?Interactive version of problem and solution.

## Monday, December 1, 2008

### December 1, 2008

Blake and Jenny each took four 100-point tests. Blake averaged 78 on the four tests. Jenny scored 10 points higher than Blake on the first test, 10 points lower than him on the second test, and 20 points higher on both the third and fourth tests. What is the difference between Jenny's average and Blake's average on these four tests?

Subscribe to:
Posts (Atom)