CS2984: Introduction to Problem Solving
Homework Assignment 9

Due at 11:00pm on Tuesday, March 25
50 Points

Here are the problems for Homework 9.

For the first five problems, you must indicate what numbers or values best fill in the blanks. You must also provide a complete description for the pattern. 

  1. 1  2  3  6  11  20  37 ___  ___  ___
  2. 4  14  21  26  36  43  48  58  65  ___  ___  ___
  3. 7  3  4  8  4  5  10  6  7  14  10  11  22  ___  ___  ___
  4. c i o d j p e k q ___ ___
  5. u n g t m f s ___ ___

The following five problems are exercises in lateral thinking. Be assured that each problem has an answer, and once discovering (or hearing) the answer, most people would be satisfied that it is "correct." They are all similar in that they tend to be difficult due to natural "blind" spots in comprehension. Answers should not require any bizarre interpretation of the question, nor any strained or unusual circumstances in the explanation.

  1. A woman drives home from work at 1:30 each working day. She normally takes an hour to get home each day, arriving at 2:30. One day she left work as usual, took the usual route, under the usual conditions. But instead of arriving home at 2:30, she arrived home at 3:30. Nothing strange happened to her -- no accident, heavy traffic, or anything like that. What explains this?
  2. The trip from Paul's house to Cindy's house is 5 miles. The trip from Cindy's house to Paul's house is 25 miles. Both trips are as short as possible. How can this be?
  3. Acting on an anonymous phone call, the police raid a house to arrest a suspected murderer. They don't know what he looks like but they know his name is John and that he is inside the house. The police bust in on a carpenter, a truck driver, a mechanic and a plumber all playing poker. Without hesitation or communication of any kind, they immediately arrest the plumber. How do they know they've got their man?
  4. How could a (normal, human) baby (accidently!) fall out of a twenty-story building onto the ground and live?
  5. There are three cookies in a box. Three children each take one of the cookies (each gets a whole cookie). How can it be that one cookie is left in the box?