190 



FARM ARITHMETIC. 



t.600 sq.ft. 



1.600 sq.ft. 



1.600 sq.ft. 



80' 



The Area Is Just the Same. 



If each were a silo, and you bought the lumber, would there be any difference 



in quantity required? 



675. What is the distance around (the perimeter of ) a 

 circular silo 20 feet in diameter ? 



Process : Multiply the diameter by 3.1416. 



Note. — The number 3.14 as multiplier is sufficiently accurate 

 for most farm work. 



20 X 3.14 = 62.8 Feet. 



676. What is the base area of a circular silo 20 feet 

 in diameter? 



Process: Multiply the square of the diameter by 0.7854 or 

 the square of the radius by 3.1416 or 3.14. 



20 X 20 X 0.7854 = 314 Square feet. 



677. What is the area of a circular silo 12 feet in 

 diameter? 25 feet? 32 feet? 40 feet? What is the 

 perimeter in each case? 



678. W^hat is the diameter of a circular silo having a 

 base or surface area of 1,G00 square feet? 



Process: Divide the area bj^ 0.7854 and take square root of 

 the result. 



1,600 -^ 0.7854 = 2.024 V2,024 = 45.1 Feet, diameter. 



679. What is the circumference or distance around 

 the inside wall of a silo having a surface area of 1,600 

 square feet? 



680. ^^'hat is the distance around a square silo con- 

 taining a surface area of 1,600 scjuare feet? 



