Question

Three cubes each of side 10 cm are joined end to end. What is the surface area of the resultant figure?

Answer 1

Answer:

Step-by-step explanation:Three cubes of edge 10 cm are joined to form a cuboid-

Therefore,

Length of cuboid (l)=10+10+10=30cm

Breadt of cuboid (b)=10cm

Height of cuboid (h)=10cm

∴ Total surface area of cuboid (A)=2(lb+bh+hl)

⇒A=2[(30×10)+(10×10)+(10×30)]

⇒A=2(300+100+300)

⇒A=1400cm  

2

 

Hence the surface area of resulting cuboid is 1400cm  

2

.

As the side of each small cube is 10cm.

Therefore, the area of each small cube (a) will be-

a=6(side)  

2

 

⇒a=6×10  

2

=600cm  

2

 

Sum of surface area of all three cubes =600+600+600=1800cm  

2

 

Now, ratio of surface are of resulting cuboid to the sum of the surface areas of three cube =  

1800

1400

​  

=  

9

7

​  

 

Hence the ratio of surface are of resulting cuboid to the sum of the surface areas of three cube is 7:9.

Answer 2

7:9 is answer

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