Question

9.
A closed metallic cylinder has its base diameter 56 cm and it is 2.25 m high. Find
the cost of the metal used to make it if it costs 80 per square metre.
​

Answer 1

Answer :

• Rs. 356.224 is the cost of metal used to make it.

Given :

• A closed metallic cylinder has its base diameter 56cm and it is 2.25 m high

To find :

• Cost of metal used to make it if the cost 80 per square metre

Solution :

First we need to find the radius then after we must use the formula of total surface area of cylinder

Finding the radius :

• Diameter = 56cm

We know that, Radius = Diameter/2

➞ 56/2

➞ 28 m

➞ 0.28 m

Radius is 0.28m

Given

• Radius = 0.28m
• Height = 2.25m

Finding the total surface area of closed metallic cylinder :

We know that

• Total Surface area of cylinder = 2πr(r + h)

Where,r is radius and h is height

➞ Total Surface area of cylinder = 2πr(r + h)

➞ 2 × 22/7 × 0.28 (0.28 + 2.25)

➞ 2 × 22/7 × 0.28 × 2.53

➞ 1.76 × 2.53

➞ 4.4528 m²

Hence, Total surface area of closed metallic cylinder = 4.4528 m²

Finding the cost of the metal :

Given,

• Cost 80 per square

➞ 4.4528 × 80

➞ 356.224 . Rs

Hence, Rs. 356.224 is the cost of metal used to make it.