Question

Question 11 (Multiple Choice Worth 2 points)

(Scale Factor MC)
An engineer has a 60:1 scale drawing of a bridge. The dimensions of the scaled bridge deck are 48 inches by 4 inches. What is
the area of the actual bridge deck in square feet?
O5,280 square feet
O2,640 square feet
288 square feet
O240 square feet
2

Answer 1

4800 ft²

or

5280 ft²

Explanation:

The deck is 48 inches by 4 inches in the drawing.

The scale is 60:1, so the real dimensions are 60 times greater than the drawing dimensions.

Let's calculate the real dimensions and also convert to feet from inches.

length = 48 in. × 60 × (1 ft)/(12 in.) = 240 ft

width = 4 in. × 60 × (1 ft)/(12 in.) = 20 ft

The real dimensions of the deck are 240 ft by 20 ft.

area = length × width

area = 240 ft × 20 ft = 4800 ft²

If the correct drawing width is really 4 2/5 in., then the real area is:

48 in. × 4 2/5 in. × 60 × 60 / 144 ft²/in.² = 5280 ft²