PSAT Math : Rectangles

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #21 : Rectangles

George wants to paint the walls in his room blue.  The ceilings are 10 ft tall and a carpet 12 ft by 15 ft covers the floor.  One gallon of paint covers 400 ft^{2} and costs $40.  One quart of paint covers 100 ft^{2} and costs $15.  How much money will he spend on the blue paint?

Possible Answers:

Correct answer:

Explanation:

The area of the walls is given by

One gallon of paint covers 400 ft^{2} and the remaining 140 ft^{2} would be covered by two quarts.

So one gallon and two quarts of paint would cost

Example Question #4 : How To Find The Area Of A Rectangle

Daisy gets new carpet for her rectangluar room.  Her floor is 21\ ft \times 24\ ft.  The carpet sells for $5 per square yard.  How much did she spend on her carpet?

Possible Answers:

\$225

\$350

\$120

\$310

\$280

Correct answer:

\$280

Explanation:

Since 3\ ft=1\ yd the room measurements are 7 yards by 8 yards.  The area of the floor is thus 56 square yards.  It would cost 5\cdot 56=\$280.

Example Question #1 : How To Find The Area Of A Rectangle

The length of a rectangular rug is five more than twice its width.  The perimeter of the rug is 40 ft.  What is the area of the rug?

Possible Answers:

150\ ft^{2}

125\ ft^{2}

75\ ft^{2}

100\ ft^{2}

50\ ft^{2}

Correct answer:

75\ ft^{2}

Explanation:

For a rectangle, P=2w+2l and A=lw where w is the width and l is the length.

Let x=width and 2x+5=length.

So the equation to solve becomes 40=2x+2(2x+5) or 40=6x+10.

Thus x=5\ ft and 2x+5=15\ ft, so the area is 75\ ft^{2}.

Example Question #1 : Rectangles

The front façade of a building is 100 feet tall and 40 feet wide.  There are eight floors in the building, and each floor has four glass windows that are 8 feet wide and 6 feet tall along the front façade.  What is the total area of the glass in the façade?

Possible Answers:

768 ft2

1536 ft2

192 ft2

1536 ft2

2464 ft2

Correct answer:

1536 ft2

Explanation:

Glass Area per Window = 8 ft x 6 ft = 48 ft2

Total Number of Windows = Windows per Floor * Number of Floors = 4 * 8 = 32 windows

Total Area of Glass = Area per Window * Total Number of Windows = 48 * 32 = 1536 ft2

Example Question #21 : Rectangles

Rectangle

Note: Figure NOT drawn to scale

What percent of Rectangle  is pink?

Possible Answers:

Correct answer:

Explanation:

The pink region is Rectangle . Its length and width are

so its area is the product of these, or

.

The length and width of Rectangle  are

so its area is the product of these, or

.

We want to know what percent 117 is of 240, which can be answered as follows:

Example Question #322 : Plane Geometry

Rectangle

Note: Figure NOT drawn to scale

Refer to the above diagram. 

40% of Rectangle  is pink.  .

Evaluate .

Possible Answers:

Correct answer:

Explanation:

Rectangle  has length  and width , so it has area

.

300 is 40% of, or 0.40 times, the area of Rectangle , which we will call . We can determine  as follows:

.

The length of Rectangle  is

,

so its width is 

.

Since 

,

Example Question #321 : Plane Geometry

Rectangle

Note: Figure NOT drawn to scale

What percent of Rectangle  is white?

Possible Answers:

Correct answer:

Explanation:

The pink region is Rectangle . Its length and width are

so its area is the product of these, or

.

The length and width of Rectangle  are

so its area is the product of these, or

.

The white region is Rectangle  cut from Rectangle , so its area is the difference of the two:

.

So we want to know what percent 162 is of 450, which can be answered as follows:

Example Question #21 : Rectangles

Rectangle

Note: Figure NOT drawn to scale

Give the ratio of the perimeter of Rectangle  to that of Rectangle .

Possible Answers:

Correct answer:

Explanation:

The perimeter of Rectangle  is

Opposite sides of a rectangle are congruent, so 

and 

 

The perimeter of Rectangle  is 

Opposite sides of a rectangle are congruent, so

,

,

and

The ratio of the perimeters is

 - that is, 7 to 5.

Example Question #21 : Rectangles

Garden

Note:  Figure NOT drawn to scale

Refer to the above figure, which shows a rectangular garden (in green) surrounded by a dirt path (in orange) eight feet wide throughout. What is the area of that dirt path?

Possible Answers:

The correct area is not given among the other responses.

Correct answer:

Explanation:

The dirt path can be seen as the region between two rectangles. The outer rectangle has length and width 100 feet and 60 feet, respectively, so its area is 

 square feet.

 

The inner rectangle has length and width  feet and  feet, respectively, so its area is

 square feet.

 

The area of the path is the difference of the two:

 square feet.

Example Question #21 : Rectangles

Garden

Refer to the above figure, which shows a rectangular garden (in green) surrounded by a dirt path (in orange). The dirt path is seven feet wide throughout. Which of the following polynomials gives the area of the dirt path in square feet?

Possible Answers:

Correct answer:

Explanation:

The area of the dirt path is the difference between the areas of the outer and inner rectangles.

The outer rectangle has area

 

The area of the inner rectangle can be found as follows:

The length of the garden is  feet less than that of the entire lot, or 

;

The width of the garden is  less than that of the entire lot, or 

;

The area of the garden is their product:

 

Now, subtract the areas:

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