All questions
Question 1
A farmer has 200 feet of fencing to make a rectangular pen for his sheep. He wants the length to be 20 feet longer than the width. How much area will the sheep have to graze?
- 2,400 square feet (correct answer)
- 2,100 square feet
- 1,800 square feet
- 2,000 square feet
Explanation: The pen's perimeter is 200 feet, so the length and width must add up to 100 feet. Since the length is 20 feet more than the width, two widths plus 20 equals 100 feet, making the width 40 feet and the length 60 feet. Multiplying 40 by 60 gives an area of 2,400 square feet. Choices B, C, and D come from mixing up the extra 20 feet or misreading which side is longer, leading to a smaller total area.
Question 2
Maya is drawing a rectangle for a classroom project. The area is 84 square feet, and the width is 7 feet. The area formula is A=L×W. What is the length of the rectangle?
- 12 feet (correct answer)
- 77 feet
- 7 feet
- 91 feet
Explanation: The correct length is 12 feet, because area equals length times width, so 84 divided by 7 equals 12. Choice B, 77 feet, comes from multiplying 7 and 11 instead of dividing 84 by 7. Choice C, 7 feet, just repeats the given width instead of solving for the length. Choice D, 91 feet, comes from adding 84 and 7 instead of dividing.
Question 3
A rectangular tile floor uses 84 square tiles. The tiles are 1-foot squares, and the tiles are arranged in 7 rows. How many tiles are in each row?
- 12 tiles (correct answer)
- 13 tiles
- 7 tiles
- 77 tiles
Explanation: Dividing the total number of tiles by the number of rows gives 84 divided by 7, which equals 12 tiles in each row. Choice B comes from a small arithmetic slip in the division. Choice C repeats the number of rows instead of finding the number of tiles per row. Choice D comes from subtracting instead of dividing the two given numbers. Choice A correctly divides the total tiles by the number of rows.
Question 4
Keisha is putting a border around a rectangular garden plot. The perimeter is 40 meters, and the width is 8 meters. Remember: perimeter =2× length +2× width. What is the length?
- 20 meters
- 32 meters
- 16 meters
- 12 meters (correct answer)
Explanation: The correct answer is 12 meters, because half the perimeter is 20 meters, and subtracting the width of 8 meters leaves a length of 12 meters. Choice A, 20 meters, stops at half the perimeter without subtracting the width. Choice B, 32 meters, comes from subtracting the width from the full perimeter instead of half the perimeter. Choice C, 16 meters, comes from dividing the perimeter by a wrong factor instead of following the correct steps.
Question 5
Yuki is building a fence around a rectangular yard. The perimeter is 60 feet, and the width is 11 feet. Remember: perimeter =2(L+W). What is the length?
- 30 feet
- 49 feet
- 19 feet (correct answer)
- 8 feet
Explanation: The correct answer is C, 19 feet. Using the formula perimeter = 2(L + W), 60 = 2(L + 11), so L + 11 = 30, and L = 19. Choice A, 30 feet, is the value of L + 11 before subtracting the width. Choice B, 49 feet, comes from subtracting the width from the perimeter instead of dividing by 2 first. Choice D, 8 feet, comes from a subtraction error.
Question 6
Jamal is building a fence around a rectangular yard. The perimeter is 48 feet, and the width is 10 feet. Remember: perimeter =2× length +2× width. What is the length of the yard?
- 38 feet
- 24 feet
- 10 feet
- 14 feet (correct answer)
Explanation: The correct length is 14 feet, because perimeter equals 2 times length plus 2 times width, so 48 minus 2 times 10 leaves 28, and 28 divided by 2 is 14. Choice A, 38 feet, comes from subtracting the width once instead of twice. Choice B, 24 feet, comes from dividing the perimeter by 2 without first subtracting the width. Choice C, 10 feet, mistakenly repeats the given width instead of solving for the length.
Question 7
Marcus is buying a rectangular rug for his room. The rug needs an area of 60 square meters, and it must be 12 meters long. Use A=L×W to find the width needed. How wide should the rug be?
- 5 meters (correct answer)
- 12 meters
- 72 meters
- 48 meters
Explanation: Since A=L×W, the width is 60÷12=5 meters. Choice B repeats the rug's given length (12 meters) instead of solving for the width. Choice C comes from multiplying 12×6 rather than dividing, which doesn't match what the problem is asking. Choice D comes from subtracting the length from the area (60−12=48) instead of dividing. Question 8
Two rectangles have the same perimeter of 32 meters. Rectangle A has a width of 6 meters. Rectangle B has a width of 8 meters. What is the difference between their areas?
- 8 square meters difference in area
- 16 square meters difference in area
- 4 square meters difference in area (correct answer)
- 12 square meters difference in area
Explanation: Since the perimeter is 32 meters, length plus width equals 16 for each rectangle. Rectangle A has width 6, so its length is 16−6=10 and its area is 6×10=60 square meters. Rectangle B has width 8, so its length is 16−8=8 and its area is 8×8=64 square meters. The difference in area is 64−60=4 square meters. Choices A, B, and D all miscalculate one or both rectangles' dimensions or areas, giving a difference other than the actual 4 square meters. Question 9
A rectangular garden bed has a perimeter of 48 feet. The width is 10 feet. Remember: perimeter =2× length +2× width. What is the length?
- 38 feet
- 24 feet
- 14 feet (correct answer)
- 28 feet
Explanation: Choice C is correct because half of the perimeter, 48 divided by 2, is 24, and 24 minus the width of 10 feet gives a length of 14 feet. Choice A is incorrect because it does not correctly apply the perimeter formula. Choice B is incorrect because it is equal to half the perimeter without subtracting the width. Choice D is incorrect because it does not match the correct subtraction of 24 minus 10.
Question 10
Keisha is covering a rectangular floor with square tiles that are 1 foot by 1 foot. She uses 48 tiles total, arranged in 6 equal rows. How many tiles are in each row?
- 6 tiles
- 54 tiles
- 42 tiles
- 8 tiles (correct answer)
Explanation: Each row has 8 tiles because 48 total tiles divided by 6 rows equals 8. Choice A confuses the number of rows with the number of tiles per row. Choice B adds instead of dividing. Choice C subtracts the number of rows from the total instead of dividing.
Question 11
Sofia is making a rectangular poster. The area is 72 square inches, and the length is 18 inches. Use A=L×W to find the width. What is the width of the poster?
- 4 inches (correct answer)
- 18 inches
- 90 inches
- 54 inches
Explanation: The width is 4 inches because 72 divided by 18 equals 4, using A = L x W solved for W. Choice B repeats the given length instead of solving for the width. Choice C adds the area and length together (72 + 18 = 90) instead of dividing. Choice D subtracts the length from the area instead of dividing (72 minus 18 = 54).
Question 12
Carlos is planning a rectangular garden plot. The perimeter is 40 feet, and the length is 16 feet. What is the width of the garden plot?
- 4 feet (correct answer)
- 24 feet
- 16 feet
- 20 feet
Explanation: 4 feet is correct because 40=2×16+2×4. 24 feet is incorrect because it results from subtracting the length from the perimeter instead of solving for width. 16 feet is incorrect because it repeats the length instead of finding the width. 20 feet is incorrect because it results from dividing the perimeter by 2 without subtracting the length. Question 13
Sofia is making a rectangular poster. The area is 72 square inches, and the length is 18 inches. Use the formula A=L×W. What is the width of the poster?
- 4 inches (correct answer)
- 18 inches
- 90 inches
- 54 inches
Explanation: The correct answer is 4 inches, because area equals length times width, so 72 divided by 18 equals 4. Choice B, 18 inches, mistakenly repeats the given length instead of solving for the width. Choice C, 90 inches, comes from adding 72 and 18 instead of dividing. Choice D, 54 inches, comes from subtracting 18 from 72.
Question 14
Yuki is making a rectangular poster board. The area is 120 square inches, and the width is 8 inches. The area formula is A=L×W. What is the length of the poster board?
- 15 inches (correct answer)
- 112 inches
- 8 inches
- 16 inches
Explanation: Since area equals length times width, 120 equals length times 8, so the length is 120 divided by 8, which is 15 inches, making Choice A correct. Choice B, 112 inches, does not come from dividing 120 by 8 or from any other operation suggested by the problem. Choice C, 8 inches, is simply the given width repeated as the answer, not the length. Choice D, 16 inches, is close to the correct value but likely comes from a small error while dividing. Dividing the area by the given width gives the correct length.
Question 15
Chen is shopping for a rectangular rug. The rug needs an area of 12 square meters, and the length is 4 meters. The area formula is A=L×W. How wide does the rug need to be?
- 3 meters (correct answer)
- 4 meters
- 16 meters
- 8 meters
Explanation: 3 meters is correct because 12÷4=3. 4 meters is incorrect because it repeats the length instead of finding the width. 16 meters is incorrect because it adds the area and length instead of dividing. 8 meters is incorrect because it subtracts the length from the area instead of dividing. Question 16
Amir is cutting a rectangular poster board. The area is 48 square inches, and one side (the width) is 12 inches. Use A = L x W to find the length. What is the length?
- 60 inches
- 36 inches
- 12 inches
- 4 inches (correct answer)
Explanation: Dividing the area by the known width gives the length: 48 / 12 = 4 inches. Choice C (12 inches) repeats the given width instead of solving for the length. Choices A (60 inches) and B (36 inches) come from adding or subtracting the given numbers instead of dividing.
Question 17
Emma is measuring a rectangular classroom floor. The area is 96 square feet, and the length is 12 feet. The area formula is A=L×W. What is the width of the classroom?
- 108 feet
- 8 feet (correct answer)
- 84 feet
- 12 feet
Explanation: The correct answer is 8 feet, because area equals length times width, so 96 divided by 12 equals 8. Choice A, 108 feet, comes from adding 96 and 12 instead of dividing. Choice C, 84 feet, comes from subtracting 12 from 96. Choice D, 12 feet, mistakenly repeats the given length instead of solving for the width.
Question 18
Chen is building a fence around a rectangular yard. The perimeter is 56 feet, and the length is 18 feet. Remember: perimeter =2(L+W). What is the width?
- 38 feet
- 28 feet
- 20 feet
- 10 feet (correct answer)
Explanation: This question tests 4th grade application of rectangle area and perimeter formulas to find missing dimensions (CCSS.4.MD.3). The area formula A = L × W means length times width equals area. To find a missing dimension when area is known, divide the area by the known dimension. For perimeter P = 2L + 2W, find the sum of both dimensions (P ÷ 2), then subtract the known dimension to find the unknown dimension. The rectangular yard has a perimeter of 56 feet and a length of 18 feet, requiring students to find the width. Choice A is correct because half the perimeter minus known length gives width: (56 ÷ 2) - 18 = 10 feet, demonstrating understanding the formula as an equation to solve for the unknown. Choice B represents not subtracting correctly: 56 ÷ 2 = 28, which happens when students forget to subtract the known dimension after dividing. To help students: For perimeter, draw rectangles and label all four sides to show why the formula is 2L + 2W. Have students write out the formula with known values plugged in, then solve for the unknown. Watch for: students who forget to divide perimeter by 2 before subtracting, and students who confuse area (square units) with perimeter (linear units).