Unit 7 · Data and Percentage

Dog Park Survey — Count the Legs

Lesson 3 of 9

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About this lesson

60 legs in a dog park, 8 owners — some with 1 dog, some with 2. No one tells you how many of each, but two simple equations crack it. The secret: every extra dog adds exactly 4 legs.

Chapters

0:00Introduction
0:24Question
0:56Strategy
1:37Step 1: Set up the two equations
2:23Step 2: Solve and verify
3:13Step 3: Alternative Method — Supposition
3:39Step 4: Supposition — assume all owners have 1 dog
4:24Step 5: Supposition — adjust and find the answer
5:09Correct answer

Question

Yesterday, in the dog park, I saw 8 dog owners exercising their dogs.

Some of the dog owners had 1 dog, and some dog owners had 2 dogs.

Counting the legs of the dogs and the legs of the dog owners, there were a total of 60 legs.

All dogs have 4 legs and all dog owners have 2 legs.

How many dog owners had only 1 dog?

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