Question

The diagram shows a cylindrical water tank of diameter 4.2 m and height 2.5 m

The curved surface and the top of the tank need to be painted.

If one liter of paint covers 8 m2 and paint is sold in 2 liter cans, how many cans of paint are needed to paint the tank?​

Answer 1

Answer:

1 can but 575 ml will remain

Step-by-step explanation:

The area of tank is 4.2m × 2.5m = 11.4 m^2 .

1 litre paints 8m^2 .

And 1 can have 2 litres .

That means 1 can paints 8^m × 2 = 16m^2 .

But tank is 11.4 .

That means it will take decimal litres to paint .

It will take more than 1 decimal litre as the tank is 11.4 m^2 .

1 litre will paint 8m^2 then it remains 11.4 - 8 = 3.4 m^2 .

3.4

Then it will paint with 1 ------- litres = 1.425 litres.

8

So it will take 1 can of paint but it will remain 1000 - 425 = 575 ml .

So answer is 1 can .

I hope it helps you .

Answer 2

Answer:

• No. of cans of paint needed to paint the tank is 3 cans.

Step-by-step explanation:

Given that:

• Diameter of the cylindrical water tank = 4.2 m
• Height of the cylindrical water tank = 2.5 m
• The curved surface and the top of the tank is to be painted.
• One litre of paint covers 8 m².
• Paint is sold in 2 litre cans.

$\setlength{\unitlength}{1mm}\begin{picture}(5,5)\thicklines\multiput(-0.5,-1)(26,0){2}{\line(0,1){40}}\multiput(12.5,-1)(0,3.2){13}{\line(0,1){1.6}}\multiput(12.5,-1)(0,40){2}{\multiput(0,0)(2,0){7}{\line(1,0){1}}}\multiput(0,0)(0,40){2}{\qbezier(1,0)(12,3)(24,0)\qbezier(1,0)(-2,-1)(1,-2)\qbezier(24,0)(27,-1)(24,-2)\qbezier(1,-2)(12,-5)(24,-2)}\multiput(18,2)(0,32){2}{\!\!\!\!\!\sf{2.1\;cm}}\put(9,17.5){\!\!\!\!\!\!\!\!\!\!\!\!\sf{2.5\;cm}}\end{picture}$

Note :- If you cant see the above latex, kindly see the answer from web or refer to the attachment.

To Find:

• How many cans of paint are needed to paint the tank?

Solution:

Finding CSA of the cylinder:

As we know that,

• Curved surface area of cylinder = (2πrh) sq. units

Where,

• r = Radius of the cylinder
• h = Height of the cylinder

Finding radius of the cylinder,

• Radius of cylinder = Diameter/2 = 4.2/2 = 2.1 m

Substituting the values,

$\sf{\longmapsto2\times\dfrac{22}{7}\times2.1\times2.5}$

Reducing the numbers,

$\sf{\longmapsto2\times22\times0.3\times2.5}$

Multiplying the numbers,

$\sf{\longmapsto33}$

Hence, curved surface area of the cylinder is 33 m².

Finding area of the top of the cylinder:

As we know that,

• Area of circle = (πr²) sq. units

Where,

• r = Radius of the circle

Substituting the values,

$\sf{\longmapsto\dfrac{22}{7}\times2.1^2}$

$\sf{\longmapsto\dfrac{22}{7}\times2.1\times2.1}$

Reducing the numbers,

$\sf{\longmapsto22\times0.3\times2.1}$

Multiplying the numbers,

$\sf{\longmapsto13.86}$

Hence, area of the top of tank is 13.86 m².

Finding total area to be painted:

Total area to be painted = (33 + 13.86) m²

= 46.86 m²

Finding area covered by 2 litres of paint

Area covered by one litre of paint = 8 m²

Area covered by 2 litres of paint = (8 × 2) m²

= 16 m²

As,

• Paint is sold in 2 litre cans.

Therefore,

$\sf{Cans\;of\;paint\;needed=\dfrac{Total \;area\; to\; be\; painted}{Area\;covered\;by\;2\;litres\;of\;paint}}$

Substituting the values,

$\sf{=\dfrac{46.86}{16}}$

Dividing the numbers,

$\sf{=2.92}$

Hence, no. cans of paint needed are 3 cans (approx.)