Question

How many tiles of size 10cmx 20cm required to cover two sides of a wall 4 m and 2m long?

Answer 1

Number of tiles required = surface area of walls/ surface area of one tile

=(400x200)/(10x20)
=400

So, total 400 tiles will be used

Answer 2

aim : to find How many tiles of size 10cmx 20cm required to cover two sides of a wall 4 m and 2m long

=> 1st let us convert 4m and 2m into cm

1m = 100cm

so 4m = 400cm and 2m = 200cm

=>now area of wall = l *b

=>400*200

=>80000cm²



now,

area of tile = l *b

=>10 *20

=>200 cm²

no .of tiles required

=>total area of wall / total area of tile

=>80000/200

=> 400 tiles

∴∴option b is correct 

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hope it helps u......