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Measurement
Lesson 8
Measuring and Calculating
Objectives/Vocab/Tips > Examples 1 | 2 | 3 | 4 | 5 > Practice: 1 | 2 | 3 | 4 | 5 > Reflection

Example 2:

Mike is installing lights around his patio. He wants to run a wire completely around the 6 walls. The lengths of the walls are 2 3/4 feet, 10 1/2 feet, 8 1/4 feet, 9 5/8 feet, 12 3/4 feet, and 7 1/4 feet.

  • If Mike cuts the wire 50 feet long, will he have enough wire for installing the lights around his patio?

Explain in detail how you found your answer using words, numbers, and/or pictures.

This is a two point question, where 1 point is given for the answer of yes or no and then another point for your explanation and support of your answer.

Let's begin this problem by making sure we understand what it is we are looking for. You know that Mike is putting lights around his patio which has 6 sides of different lengths. He needs the wire to go around all six sides. He cuts the wire at 50 feet and you need to find out if 50 feet of wire is enough wire to install the lights.

The information you are given are the lengths of the 6 sides, 2 3/4 feet, 10 1/2 feet, 8 1/4 feet, 9 5/8 feet, 12 3/4 feet, and 7 1/4 feet. You also know that you really only have 50 feet of wire to go around the this patio.

To better see the solution, it may be easier to make a simple drawing of the patio.

One way to see if 50 feet is even close is to make an estimate by doing some rounding of the lengths of the sides. So, you would end up with:

3 ft + 11 ft + 8 ft + 10 ft + 13 ft + 7 ft = 52 ft

With the estimation, it appears Mike may not have enough wire. But you better finish solving this one so that Mike knows whether or not to spend his time putting up the wire or not.

Solving the problem, you need to rewrite the fractions as equivalent fractions with the common denominator of 8. Then add the mixed numbers. The six sides rewritten look like this:

2 6/8 + 10 4/8 + 8 2/8 + 9 5/8 + 12 6/8 + 7 2/8

Add the whole numbers first.

2 + 10 + 8 + 9 + 12 + 7 = 48

Now add the fractions.

6/8 + 4/8 + 2/8 + 5/8 + 6/8 + 2/8 = 25/8

Rewrite 25/8 as a mixed number.

3 1/8

Now you add 48 + 3 1/8 which equals 51 1/8.

As you look at your answer you notice that the distance around the patio is 51 1/8 feet. Since Mike cut the wire at 50 feet, he won't have enough wire to install the lights around the patio. Looks like Mike should have done some math first before cutting the wire!

 

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