ISEE Lower Level Math : How to find the perimeter of a rectangle

Study concepts, example questions & explanations for ISEE Lower Level Math

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Example Questions

Example Question #81 : Plane Geometry

If the perimeter of a rectangle is equal to 54 inches, what are possible values for the width and length?

Possible Answers:

Width of 10 inches and length of 16 inches

Width of 11 inches and length of 17 inches

Width of 10 inches and length of 17 inches

Width of 10 inches and length of 18 inches

None of these

Correct answer:

Width of 10 inches and length of 17 inches

Explanation:

The perimeter of a rectangle is equal to:

The only answer choice that provides dimensions for which the perimeter of a rectangle would be 54 inches is when there is a width of 10 inches a length of 17 inches.

Therefore, a width of 10 inches and length of 17 inches is the correct answer. 

Example Question #82 : Plane Geometry

If the width of a rectangle is 2 inches and the length is 6 inches, what is the perimeter in inches?

Possible Answers:

Correct answer:

Explanation:

The perimeter of a rectangle can be found by adding together all the sides. The formula is:

Use the given values for the length and the width to solve.

16 inches is the correct answer. 

Example Question #83 : Plane Geometry

A rectangle has a width of 5 inches and an area of 35 inches. What is the length, in inches?

Possible Answers:

Correct answer:

Explanation:

The area of a rectangle is equal to the length times the width. 

Here, we know that the area is 35, and the width is 5. We can fill in part of the equation with these values.

The only number that equals 35 when multiplied by 5 is 7.

7 is the correct answer. 

Example Question #84 : Plane Geometry

If the width of a rectangle is 3 inches and the length is 5 inches, what is the perimeter?

Possible Answers:

Correct answer:

Explanation:

The perimeter of a rectangle can be found by adding together all the sides. This would give us:

Therefore, 16 inches is the correct answer. 

Example Question #11 : How To Find The Perimeter Of A Rectangle

Marcell wants to put a new fence around the perimeter of his garden. Marcell's rectangular garden is 30 feet long and 15 feet wide. How many feet of fence does Marcell need?

Possible Answers:

\dpi{100} 90\ feet

\dpi{100} 50\ feet

\dpi{100} 45\ feet

\dpi{100} 60\ feet

Correct answer:

\dpi{100} 90\ feet

Explanation:

\dpi{100} (30+30)+(15+15)

Example Question #12 : How To Find The Perimeter Of A Rectangle

The length of a rectangle is , and the width of the rectangle is . What is the perimeter if  and ?

Possible Answers:

Correct answer:

Explanation:

If the length of a rectangle is  and the width is , the perimeter is:

Now plug in  and :

Example Question #13 : How To Find The Perimeter Of A Rectangle

If the perimeter of a rectangle is  inches and its length is twice the value of its width, what is the value of the width of the rectangle in inches?

Possible Answers:

 inches

 inches

 inches

 inches

Correct answer:

 inches

Explanation:

If the length of the rectangle is twice the value of its width, then if the width is equal to w, then the length is equal to 2w. 

Given that the perimeter of a rectangle is equal to the value of all the sides added together, the following equation would apply:

This means that the rectangle is  inches wide.

Example Question #14 : How To Find The Perimeter Of A Rectangle

The area of a rectangle is . One of its sides is . What is its perimeter?

Possible Answers:

Correct answer:

Explanation:

Remember that the area of a rectangle is equal to its base times its height. If its area is  and one side has a length of , we can find the other side by dividing these:

So, our rectangle looks like this:

Untitled_7

The perimeter is easily calculated:

Example Question #15 : How To Find The Perimeter Of A Rectangle

What is the perimeter of the following rectangle?

Untitled_8

 

Possible Answers:

631.1

199.3

Correct answer:

Explanation:

The perimeter of a rectangle is very easy to solve.  Merely add up all the sides:

Example Question #16 : How To Find The Perimeter Of A Rectangle

One of a rectangle's sides has a length of . Another of its sides is half that length. What is its perimeter?

Possible Answers:

Correct answer:

Explanation:

If one side of the rectangle is  and the other half of that, then the other side must be:

Our rectangle therefore looks like this:

Untitled_9

The perimeter is calculated very easily.  Just sum up all the sides!

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