History

Watson Wyatt traces its roots back to the oldest actuarial firm in the world.

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At full pelt, water gushes out of a tap at 7.5 litres a minute. If the overflow is blocked and it takes 90 seconds for a 6-litre sink full to go down the plughole, how long to the nearest second until the sink starts to overflow?

Every minute 7.5 litres are entering the sink, while 4 litres are draining. Therefore the sink is filling by 3.5 litres each minute. If the sink has a 6 litre capacity, then it will become full and start to overflow after 103 seconds.


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