Question

A solid metallic hemisphere has diameter 42
cm. Find the cost of polishing the total surface at
the rate 20 paise per cm2.
A
​

Answer 1

SOLUTION

Diameter of hemisphere= 42cm

Radius of hemisphere= 42/2= 21cm

Total surface area of hemisphere= 3πr^2

=) 3× 22/7× 21^2

=) 3× 22× 3× 21

=) 4158cm^2

Cost of polishing 1 sq.cm is 20 Paisa

=) cost of polishing 4158cm^2

=) 4158× 20

=) 83160 paise

=) 100 paise= 1rupees

=) 83160paise= 83160/100

=) 831.6 Rupees

Therefore the cost of polishing it's total surface is 831.6Rs.

hope it helps ☺️⬆️