Problem Solving 1

Steps to world problem solving process 1. Understand the Problem 2. Devise a plan 3. Carry out the plan 4. Look back 5. MAKE SURE YOU ANSWER THE QUESTION 2

Understand the problem Understand? Enough info 3

Devise a plan Guess and test Look for pattern Use algebra Make it simple 4

Carry out the plan Implement Don’t be afraid to start over 5

Look back Correct solution? 6

Answer the question Check to see if you answered the right question 7

Problem 1 Place the digits 1,2,3,4,5, and 6 in the circles below so that the sum of the three numbers on each side is 12. 8

Solution Look for pattern Listing special cases will help you

Problem 2 10

Problem 3 There are 20 people at the meeting. If each person shakes hands with every person (except himself) in the room only once, how many handshakes will there be? What if there were 2 people? 3? 4? 2=1 shakes 3=3 shakes 4=6 shakes 5=10 shakes n=n(n-1)/2 20=190 11

Problem 4 A merchant has a basket of oranges, and sells half of them to the first person and then gives him one more for good measure. He then sells half the remaining oranges to the second person and gives him an extra orange for good measure. A third person buys exactly half the remaining oranges and the vendor gives him one more for good measure. Finally the merchant eats the last orange. How many oranges were originally in the basket? 22 oranges 12

Problem 5 What is the greatest number that divides the sum of any three consecutive whole numbers, without leaving an remainder? Understand the problem Consecutive whole numbers by 1 Devise a plan If n represents the first number, what are the next two? Carry out the plan n+(n+1)+(n+2)= 3n+3= 3(n+1), this number is divisible by 3. 13

Problem 6 How many ways can the letter A, B, and C be arranged? 6 ways 14

Slide Example: Drawing a Sketch An array of nine dots is arranged in a 3 x 3 square as shown below. Join the dots with exactly four straight lines segments. You are not allowed to pick up your pencil from the paper and may not trace over a segment that has already been drawn.

Slide Example: Solution Through trial and error with different attempts such as We find an answer is

Slide Example: Using Common Sense Two currently minted United States coins together have a total value of $0.30. One is not a quarter. What are the two coins? Solution This involves a “catch.” The two coins are a quarter and a nickel. Note that one of the coins is not a quarter, it is a nickel.

Slide Example: Guessing and Checking Find a positive natural number that satisfies the equation below.

Slide Example: Solution Try this by guess and check: Solution x = 16 satisfies the equation.

HW section 1.5 pg ,