PROBLEM 1-7-4

The number of times a dog barks depends on the number of cars passing. 

How many cars have passed when a dog barks 22 times?  How many barks for 5 cars?

CARS

BARKS

6

4

7

7

8

10

9

13

10

16

SOLUTION 1-7-4

Looking at the table, every time another car passes, there are 3 more barks.  Therefore the dog barks 6 more times which would equal 2 more cars passing, so 12 cars passed when the dog barked 22 times. 

If one less car passed, then there would be 3 less barks.  So, when 5 cars pass, the dog only barks 1 time.