posted by lissa .
A swimming pool has two identical sides in the shape of a trapezium.
All other sides are rectangular.
The length of the pool is 12m.
The width of the pool is 4m.
The depth of the pool is 2.1m at the deep end and 1.1m at the shallow end.
Rafa fills the pool up with water from a hosepipe.
The surface of the water is to be 10cm from the top of the pool.
Rafa turns on the hosepipe at09 00 on Monday and water fills at a rate of 200ml per second.
When the pool is full, Rafa turns of the tap. At what time wil this be?
Show your working out.
I visualize two trapezoids as the side walls and rectangles as the end walls.
Volume = area of side wall x width
= 12 ((1.1 + 2.1)/2) ( 4) = 76.8 m^3
= 76.8(1000) L
= 76800 L
200 ml/sec = .2 L/sec
so time taken = 76800/.2 seconds
= 384000 seconds
= 6400 minutes
= 106.6667 hours or 4.44444.. days
= 4 days, 10 hours , 40 minutes
I will let you compute the time he turns off the tap