Question

The perimeter of a building is 900 feet. If the length of the building is 400 feet, find the width. How many lights will be needed if they are to be placed every 15 feet around the building?

Answer 1

The width is 50 feet.

60 lights.

Explanation:

The perimeter can be calculated as:

P = 2*L + 2*W,

where P is the perimeter, L is the length and W is the width.

Using this formula, we have that:

900 = 2*400 + 2*W

2*W = 100 -> W = 50 feet

If we use one light for every 15 feet around the building, we can find the total number of lights using rule of three:

15 feet -> 1 light

900 feet -> X lights

15/900 = 1/X

X = 900/15 = 60 lights

Answer 2

The width of the building is 50 lamps and 60 lamps will be needed.

Explanation:

The perimeter is computed by the sum of the sides of the building, since the length and width are equal on the oposite sides of the building, the perimeter is given by:

perimeter = 2*length + 2*width

900 = 2*(400) + 2*width

2*width + 800 = 900

2*width = 900 - 800

2*width = 100

width = 100/2 = 50 feets

To know how many lights bulbs will be needed we need to take the perimeter of the building and divide it by the space between the lamps. We have:

number o lamps = 900/15 = 60 lamps