42 PRACTICAL MEASUREMENTS 



wire. What is the cost of the fence when posts cost 15$ 

 each, woven wire 23$ per rod, and barbed wire 1.8$ per rod? 

 4. A fence answering the same purpose could have been 

 built with the same number of posts at the same price, using 

 woven wire 48 in. high at 27$ per rod. What would have 

 been the difference in the cost of the two fences ? 



AREAS OF STATES 



47. Maps are drawn to a scale, that is, 1 in. on a map 

 may be used to represent 80, 90, or 100 mi., etc. From 

 the scale of a map the area of the surface represented 

 may be determined. 



48. Rule. To determine approximately the area of a state 

 or a county from a map drawn to a scale, square the number 

 represented by 1 in. on the scale and multiply the product by 

 the number of square inches in the map. The result will be 

 the area in square miles. If the state is irregular in shape, 

 use an average length and width. 



EXERCISE 



1. A square surface 4 ft. long is represented by a drawing 

 1 ft. square. In what ratio are the dimensions diminished ? 

 The surface of the drawing (1 sq. ft.) represents how many 

 square feet of the original surface ? 



2. A square surface 3 ft. long is represented by a draw- 

 ing 1 ft. square. In what ratio are the dimensions dimin- 

 ished? The surface of the drawing represents how many 

 square feet of the original surface ? 



3. A rectangular surface 12 in. by 8 in. is represented by 

 a drawing 3 in. by 2 in. In what ratio are the dimensions 

 diminished ? How many square inches of the original sur- 

 face does 1 sq. in. of the drawing represent ? 



