Your civil engineering firm has been contracted to lay water

Your civil engineering firm has been contracted to lay water pipes for two streets in a new neighborhood. The pipes (that will connect to the city\'s main intersection) must be able to provide 1810 gallons of water per minute to the new homes being built. The design calls for two safety valves that are each known to leak 1.35% of the water passing through them. How many gallons per minute must the water department provide at the main intersection (before entering your two pipes)? (Keep one decimal place in your answer)

Solution

There are two leaks (we assume that they are in series)

Note that the delivery should be 1810 gallons. let \'S2\' be the supply before the second leak.

So, S2 x (100% - 1.35%) = 1810

or, S2 = 1810 / (1 - 0.0135) = 1834.77 gallons

let \'S1\' be the supply before the first leak (i.e. at the main intersection).

So, S1 x (100% - 1.35%) = 1834.77

or, S1 = 1810 / (1 - 0.0135) = 1859.9 gallons