Draining a pool

The water is being drained from a pool. After how long will the depth of the pool be 144 cm?

Problem



 

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Draining a pool

Water is draining from a pool.

The graph shows the depth of the water, in centimetres, against time, in minutes.

At what time will the depth of the water be 144 cm?

 

This problem is taken from the World Mathematics Championships