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Geometry

by ROHIT11111 » Sat Apr 16, 2016 10:32 pm
1. A rectangular room is 7 metres long and 4 metres wide. Carpet tiles are 50 centimetres square. How many tiles will be needed to carpet the whole room (1 metre = 100 centimetres)? 

ans-112
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by [email protected] » Sun Apr 17, 2016 11:00 am
Hi ROHIT11111,

When posting GMAT questions, you should post the 5 answer choices with the question. Sometimes the 'design' of the answer choices can help you to avoid a long-winded 'math approach.' With just the prompt, we have no choice but to do that math. This is essentially a 'rate' question with a little bit of geometry thrown in.

We know the length and width of the room, so we know that it's area is (7)(4) = 28 square meters.

We're told that carpet tiles are 50cm x 50cm. We're asked how many tiles are needed to tile the entire room.

To start, we can 'convert' the room from square meters to square centimeters...

(7 meters)(4 meters) = (700 cm)(400 cm) = 280,000 square cm.

Each tile is (50cm)(50cm) = 2500 cm

We can now figure out how many tiles are needed...

280,000cm/2500cm = 2800/25 = 112 tiles

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by OptimusPrep » Sun Apr 17, 2016 7:59 pm
ROHIT11111 wrote:1. A rectangular room is 7 metres long and 4 metres wide. Carpet tiles are 50 centimetres square. How many tiles will be needed to carpet the whole room (1 metre = 100 centimetres)? 

ans-112
Hi ROHIT11111,

This is a fairly simple question and can be done by the concepts or areas and by keeping in mind that the units of numerator and denominator should be same.
Area of the room = (7*100)*(4*100) = 28*100*100 cm square

The dimensions of the tile can be confusing and I would say this question could have been written in a better way.
It says that the tiles are squares with a side = 50 cm.
Hence the area of each tile = 50*50 = 2500

We need to cover the room by these tiles
Hence number of tiles required = (28*100*100)/2500 = 112
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