Using work to find The amount of....

[Rajvirnijjar]

The Grand Coulee Dam is 1270 m long and 170 m high. The electrical power output from generators at its base is approximately 2010 MW.

How many cubic meters of water must flow from the top of the dam per second to produce this amount of power if 91.0 % of the work done on the water by gravity is converted to electrical energy? (Each cubic meter of water has a mass of 1000 kg.)
Take the free fall acceleration to be 9.80m/s2

I need some help on this problem, I dont know where to even start. Can some one give me some hints to start this problem.

Thanks

[Cyclovenom]

You know 91% of the work done by gravity is converted to electric energy. simply equate the Power defition to 2010 MW and find the relation Volume/time.

[Erik_at_DTU]

Think of energy equations:
E=mgh