The diameter of a 120 cm long roller is 84 cm. If it takes 1000 complete revolutions to level a playground having breadth of 32 m, find the length of the playground. 

Asked by Cl_narayan | 17th Jul, 2019, 04:23: PM

Expert Answer:

 
 
 
Radius of the roller = diameter ÷ 2 = 84 ÷ 2 = 42 cm
 
Length of the roller = 120 cm
 
Curved Surface Area of the Roller (Cylindrical shape) = begin mathsize 16px style 2 πrh space space equals space 2 space cross times 22 over 7 cross times 42 space cross times space 120 space equals space 31680 space cm squared end style

Therefore the area covered by the roller in one revolution = 31680 cm2
 
Therefore the area covered by the roller in 1000 revolutions = 31680 × 1000 = 31680000 cm2
 
Therefore the area of the play ground = 31680000 cm2 = 3168 m2
 
→ l × b = 3168
→ l  × 32  = 3168
→ l = 99 m

 

Answered by Yasmeen Khan | 17th Jul, 2019, 06:22: PM