Question

A cylindrical roller of its length 4 metre and diameter 84 CM find the number of revolutions it has to make to cover an area of of 7920 square metre​

Answer 1

Step-by-step explanation:

Given:-

A cylindrical roller of its length 4 metre and diameter 84 cm.

To find:-

find the number of revolutions it has to make to cover an area of of 7920 square metre.

Solution:-

Length of the cylindrical roller(h)=4 m

Diameter of the cylindrical roller=(d)=84 cm

Radius=diameter/2=84/2=42 cm

Radius=42/100m=0.42 m

(1 meter=100 cm)

Area of the cylindrical roller covered in one revolution=Curved surface area of the cylinder

=2πrh sq.units

here π=22/7

=>2×(22/7)×0.42×4 sq.m

=>(2×22×0.42×4)/7 sq.m

=>2×22×0.06×4 sq.m

=>10.56 sq.m

area covered by the roller in one revolution=10.56 sq.m

Let the number of revolutions done by the roller be "n".

Area covered by the roller in "n" revolutions =10.56n sq.m

Area covered by the roller =7920 sq.m

=>10.56 n=7920

=>1056n/100=7920

=>1056n=7920×100

=>1056n=792000

=>1056×n=792000

=>n=792000/1056

=>n=750

Revolutions=750

Answer:-

The required number of revolutions=750