Area Perimeter Circumference Word Problems

A kitchen floor is 35 m by 50 m. New tiles are needed for the floor. If one tile covers 25 square metres of space, how many tiles will be needed to cover the floor?

Alicia's garden is 50 square metres. Inside of her garden she plants a section of tomatoes that is 3m by 4m. How much more space does she have left in her garden to plant other crops? 

Tags

CCSS.3.MD.A.2

A triangular wall needs to be painted. The triangle is an equilateral triangle with 35 metre sides and the height of the wall is 30 metres. Nina wants to make a gold border around the wall. What is the length of the gold border that is needed?

Answer explanation

An equilateral triangle means that all 3 sides are equal. This means you need to add up all 3 sides to get the length of the gold border.

Tags

CCSS.3.MD.D.8

The garden has two sections: a triangle section for vegetables and a circular section for flowers, with the rest grass. The vegetables section is a right-angle with sides of 3.45m and 2.1m. The flower section is 5.7m from one side to the other. What is the total area of each section of the garden? If grass seed costs $1.77/m², how much will it cost to buy enough seed for the grass area?

Answer explanation

Vegetable Section (Triangle)

Area of triangle = (base × height) ÷ 2

Area = (3.45 × 2.1) ÷ 2 = 3.6225 m²

Flower Section (Circle)

Area of circle = π × r²

Where r is the radius (half the diameter) - Radius = 5.7 ÷ 2 = 2.85m

Area = π × 2.85² ≈ 25.5173 m²

Grass Section

subtract vegetable and flower areas from the total garden area.

TOTAL GARDEN AREA: 52.46m² (8.6 x 6.1)

VEGETABLE & FLOWER GARDENS:

3.6225 m² + 25.5173 m² = 29.1398m²

GRASS AREA = 52.46 - 29.1398 = 23.32m²

Grass Seed Cost = Grass area × Price per m²

         = 23.32m² × $1.77/m²  = 41.2764

         = $41.30

The school is painting a mural on a wall shaped like a trapezium. The parallel sides of the wall are 8 metres and 12 metres long, and the height between them is 5 metres. How much paint will they need if 1L covers 10 square metres?

Answer explanation

Area of trapezium

= ½(a+b)h

= ½(8+12) × 5

= 50m²

Paint needed

= 50 ÷ 10

Tags

CCSS.6.G.A.1

A church is commissioning a circular stained glass window with a smaller circular design in its centre. The outer circle has a radius of 2.4 metres, while the inner circle has an area that is 1/9 of the total window area. What is the radius of the inner circle?

Answer explanation

Area of outer circle

= πr² = π(2.4)² = 18.1 m² (rounded to one dp)

Area of inner circle

=The inner circle's area is 1/9 of the total area

   =  18.1 ÷ 9 = 2.01 m²

use the area formula for a circle to find the radius of the inner circle:

   2.01 = πr²

   r² = 2.01 ÷ π

   r = √(2.01 ÷ π) ≈ 0.8 m

A farmer notices a mysterious crop circle in his field. It's composed of two circles: a larger outer circle and a smaller inner circle. The area between the two circles is 200 square metres. If the radius of the larger circle is 10 metres, what is the radius of the smaller circle?

Answer explanation

 Area between circles

= π(R² - r²) = 200

=  π(10² - r²) = 200

= 100π - πr² = 200

=  πr² = 100π - 200

= r² = 100 - 200/π ≈ 36.34

A new skateboard park is being designed in the shape of a trapezium. The parallel sides are 58m and 45m long, and the non-parallel sides are both 50m long. Inside the park, a circular area with a radius of 18 metres will be set aside for beginners. What percentage of the total park area is the beginners' circle?

Answer explanation

  Area of trapezium = 2575m²

  Area of circle = πr² = π × 16² =  804.2477 = 804.25m²

  Percentage = (804.25 ÷ 2575) × 100 = 31.233%

Tags

CCSS.6.G.A.1

An artist is creating an installation using a square metal sheet. She cuts out a circle from the centre of the square. The area of the remaining metal (the square minus the circle) is 144cm². If the side length of the square is 14cm, what is the radius of the circular cut-out?

Answer explanation

Area of square = 14² = 196 cm²

  Area of circle =

πr² = 196 - 144  

     πr² = 52

     r² = 52 ÷ π ≈ 16.55

  Radius = 4.07 cm

What is the circumference?

• 48

• 96

• 24

• 18

Tags

CCSS.7.G.B.4