The scale drawing of a concrete pad has a length of 9.1 cm, a depth of 2.2 cm and a width of 3.8 cm. Using the scale drawing, what is the actual depth of the concrete pad if the actual width is 418 cm? Responses A 101.1 cm101.1 cm B 242 cm242 cm C 432 cm432 cm D 668.8 cm
To find the actual depth of the concrete pad, we need to first determine the scale factor.
Scale factor = Actual width / Length on scale drawing
Scale factor = 418 cm / 3.8 cm ≈ 110
Next, we need to use the scale factor to find the actual depth of the concrete pad:
Actual depth = Depth on scale drawing x Scale factor
Actual depth = 2.2 cm x 110 = 242 cm
Therefore, the actual depth of the concrete pad is 242 cm.
The correct answer is B) 242 cm.
Do you cross multiply?
Yes, to find the actual depth of the concrete pad using a scale drawing, you can use proportions. Here's how you can set it up:
First, calculate the scale factor:
Scale factor = Actual width / Length on scale drawing = 418 cm / 3.8 cm ≈ 110
Next, set up a proportion to find the actual depth:
Actual depth / 2.2 cm = 110
Actual depth = 2.2 cm x 110
Actual depth = 242 cm
So, yes, in setting up the proportions and solving for the unknown variable, you are essentially cross multiplying.