The diameter of a roller 120cm long is 48cm If it takes 350 complete revolutions to level a playground, - Maths - Mensuration

Question

T h e   d i a m e t e r   o f   a   r o l l e r
  120 c m   l o n g   i s   48 c m   I f
  i t   t a k e s   350   c o m p l e t e
  r e v o l u t i o n s   t o   l e v e l   a
  p l a y g r o u n d ,   d e t e r m i n e   t h e
  cos t   o f   l e v e l l i n g   i t  
a t   t h e   r a t e   o f   R s   15
  p e r   m 2

Neha Sethi · Accepted Answer

Dear student
Since roller is in the form of cylinder
 SoDiameter of roller=84 cmSo, radius of roller r=Diameter2=842=42 cmAnd length of roller=height of cylinder h=120 cmNow,CSA of roller =2πrh=2×227×42×120=31680 cm2Thus,  Area of playground =350×CSA of roller
=350×31680 cm2=11088000 cm2=1108
8m2    ∵1m=100cmTherefore, cost of levelling at the rate of Rs15 per meter square=Rs15×1108
8=Rs16632
Regards

T h e d i a m e t e r o f a r o l l e r 120 c m l o n g i s 48 c m . I f i t t a k e s 350 c o m p l e t e r e v o l u t i o n s t o l e v e l a p l a y g r o u n d , d e t e r m i n e t h e cos t o f l e v e l l i n g i t a t t h e r a t e o f R s . 15 p e r m 2 .

$T h e d i a m e t e r o f a r o l l e r 120 c m l o n g i s 48 c m . I f i t t a k e s 350 c o m p l e t e r e v o l u t i o n s t o l e v e l a p l a y g r o u n d, d e t e r m i n e t h e \cos t o f l e v e l l i n g i t a t t h e r a t e o f R s . 15 p e r m^{2} .$