Jenny’s old water pump could only fill 1 swimming pool in 5 hours. Her new water pump was able to fill 1 swimming pool in 3 hours. How long will it take Jenny to fill 1 swimming pool if she uses both pumps at the same time? Famous Problems (There are some major assumptions at play)

Let’s look at “Old Pump” a little closer: It fills the whole pool in 5 hours 1 Pool 5 Hours It fills the 1 / 5 of the pool in 1 hour 1 / 5 Pool 1 Hour

Let’s look at “New Pump” a little closer: It fills the whole pool in 3 hours 1 Pool 3 Hours It fills the 1 / 3 of the pool in 1 hour 1 / 3 Pool 1 Hour

In fact, if we picture our Pool like this Then we have this for Old & New Pumps… New Pump Old Pump in 1 Hour Three “Squaries” Five “Squaries” in 1 Hour

If my pumps were working together, then in 1 hour I suppose I’d get (By the way, I know that “One Squarie” is really 1 / 15 of the whole pool water ! ) = By Old Pump = By New Pump In fact, I’ll call this new action my “Two Pumps”, and I’ll make a note that these “Two Pumps” do 8 / 15 pool in 1 hour = By Two Pumps

Now I’m a little stuck, so I’ll reflect on what I do know… in 1 Hour That’s Eight “Squaries”… “Two Pumps” do 8 / 15 of the pool… …in 1 Hour

But wait! Eight Squaries in 1 Hour That is like: Four Squaries in ½ Hour That is like: Two Squaries in ¼ Hour That is like: One Squarie in 1 / 8 Hour

So, what do I need? I need to fill the pool !! I am using my special “Two Pumps” action, so my desire is for this picture: One Squarie ( ) in 1/8 Hour For 15 Squaries, I’ll need 15 of these I need 15 Squaries! But since I had (on the last page)

So for 15 Squaries (One Whole Pool) It looks like I’ll need 15 Pie Dealies…

Each Pie Dealie was 1 / 8 of an Hour So, fitting my 15 Pie Dealies together, it looks like One Hour & 7 / 8 of an Hour

My Conclusion? The powerful “Two Pumps” will fill this pool In this many hours… Which is 1 7 / 8 Hours ! Math Rules !!