Mathematics Magazine for Grades 1-12  

 

3/2004
     

Many a time I have wanted to stop talking and find out what I really believed.
 - Walter Lippmann

Grade 6

Theory:

Logic - A Story of "Or"

Let P and Q be sentences, each of which is either true or false (but neither is both; ). "P or Q" is a compound sentence, which is false only when both P and Q are false (and true in all other cases). Here is a table that lists every possible combination of truth and falseness for P and Q and states whether "P or Q" is true for each possible combination.

Truth Table For "Or"

P

Q

P or Q

T

T

T

T

F

T

F

T

T

F

F

F

Solutions from the Previous Issue:

  1. Six people in a club will share the expenses of a party that costs $240. How much will Katie pay if the club owes her $8?

Solution:

$240  6 = $40

Katie will pay: $40 - $8 = $32

  1. Jesse spends $5 a day on lunch. Which algebraic expression correctly represents the amount of money he will spend on lunch in x days?

Solution:

x∙5

  1. Which algebraic equation correctly represents this sentence?
    A number increased by eight is nineteen.

Solution:

x + 8 = 19

  1. Which algebraic equation correctly represents this sentence?
    Twenty-five is three times a number, decreased by eight.

Solution:

25 = 3x - 8

Proposed Exercises:

In each of the following proportions solve for the unknown value.

1        

2        

3        

4        

5