Question

The diagram shows the cross-section of a wall of a cinema. It has to be painted. Work out the area that needs to be painted.

Answer 1

Answer:

Area = 370 m²

Cost to paint = £105

Step-by-step explanation:

Area of the wall of a cinema hall = Area of a trapezoid (1)+ Area of a rectangle (2) + Area of a trapezoid (3)

Area of a trapezoid = $\frac{1}{2}(b_1+b_2)h$

where $b_1$ and $b_2$ are the parallel sides and h is the distance between these sides.

Area of trapezoid (1) = $\frac{1}{2}(11+12)\times 6$

                                  = 69 m²

Area of the rectangle (2) = Length × Width

                                         = 12 × 15

                                         = 180 m²

Area of the trapezoid (3) = $\frac{1}{2}(12+10)\times 11$

                                         = 121 m²

Now area of the wall = 69 + 180 + 121

                                   = 370 m²

One tin covers the area = 25 m²

Number of tins required to paint the wall = $\frac{\text{Total area}}{\text{Area covered by one tin}}$

= $\frac{370}{25}$

= 14.8

Therefore, number of tins to be purchased = 15

Cost to paint the complete wall = 15 × £7

                                                       = £105