(1) Balancing the Books:  a) Bill = 250 marbles, Mary = 150 marbles, Anne = 70 marbles
b) Bow costs $20.50. Arrow costs $0.50

(2) Rodents and Cats:  a) 6 cats can devour 100 rats in 100 minutes (6000 seconds)
b) 18 stitches

(3) Ten Per Side:

2	6	2
6		6
2	6	2

  32 men in total, ten per side.

3	4	3
4		4
3	4	3

  28 men in total, ten per side.

2		8
8		2

  20 men in total, ten per side.

(4) Car + Breakdown = Loooong Walk!:   Drives 15 times as fast as she walks

(5) Apples In A Box:   You need to take at least 7 apples to be sure of getting 3 of one kind.

(6) Shoes and Socks:   4 shoes, 3 socks.

(7) The Line:   DE = 5cm    BE = 10cm, so BC = 2.5cm.

(8) Video Competition: 

2	7	3
4	6	9
1	8	5

  Solution 1.

6	1	2
4	5	7
3	9	8

  Solution 2.

(9) Tremendous Tessellations: Answers will vary.

(10) Shaping the Problem:

The letter F could also be made, though this solution is less accurate than E.

(11) Folding the Octagon:

(12) Ingenious Ring Linking:

How to link 5 rings into a chain so that by cutting one link the whole chain comes apart.

How to link 5 links into a chain so that by cutting ANY link, the whole chain comes apart.