Question

1. to paint the walls of a rectangular room that is 10 meters long, 8 meters wide, and 2.5 meters high with two coats of paint, if one liter of paint covers 10 m², how many liters are needed?

o a. 18
o b. 36
o c. 144
o d. 72

Explanation:

Step1: Calculate the area of the walls

The formula for the lateral surface area of a rectangular room (area of the walls) is \(2\times h\times (l + w)\), where \(l = 10\)m (length), \(w = 8\)m (width), \(h=2.5\)m (height).

$$2\times2.5\times(10 + 8)=2\times2.5\times18 = 90\space m^{2}$$

Step2: Calculate the area for two - coat painting

Since there are two coats of paint, the total area to be painted is \(A = 2\times90=180\space m^{2}\)

Step3: Calculate the amount of paint

Given that one liter of paint covers \(10\space m^{2}\). Let the volume of paint be \(V\). Using the formula \(V=\frac{A}{10}\) (where \(A\) is the total area to be painted)

$$V=\frac{180}{10}=18$$

liters per coat. For two coats, \(V = 2\times18=36\) liters.

Answer:

B. 36