A Quiz

Today friends we are having a pop quiz.  Didn’t those words strike terror in your heart when you were in school?  No – maybe you all were better prepared for such things than I was.  Anyway, our quiz is easy – I promise – and guessing is allowed, perhaps even encouraged.  See the large object below that Rick and Alex are moving?

That object is a 425 gallon water trough – or in some parts of the country it is called a water tank – which is the water source for our cattle.  The trough is filled from rainwater coming off the cattle shed roof.  This system works really well as long as there is regular rain; in November we got over 14 inches of rain and it was overflowing.

So, here is our quiz question:  How many inches of rain does it take to fill the water trough?

I know you mathematical and engineering types are going to need precise information to make your calculations.  The shed is 12 deep  x 20 feet wide and the roof hangs over the edge about 2 inches on each side.  The rain gutter is a standard size that we got at Lowe’s.  The water trough is 10 feet long x 3 feet wide x 2 feet high. When we originally installed this system in November we had the rain spout running all the way down to the tank.

A couple of things didn’t work too well that way.  First, the cattle used it as a rubbing post – they seem to use anything they can reach as a rubbing post.  Second, and entirely unrelated, the first water tank was defective and when  filled with water it bulged out at the seam.  As you can see above, Rick put a strap on it to keep it together until the replacement tank came in.

I believe I have provided all the pertinent information necessary to answer the question – again: How many inches of rain does it take to fill the trough?   If I have left out some necessary part of the equation  (entirely possible) please let me know.  The quiz will be open to carefully calculated predictions and wild guesses until the 20th of December when the answer and winner will be revealed.  Please post your answers as a comment and let the games begin!  The answer closest to the correct answer without going over will be the winner.  There is an actual lovely prize for this quiz – which will be revealed in a day or two.  So, get out your slide ruler (do they will make / use those?) and get to work on your winning answer!

9 comments on “A Quiz

  1. ml says:

    ok – I have two guesses. #1. Lots #2. Less than fourteen inches. I didn’t like those kind of questions in school either.

    • Brenda says:

      I can confirm that the correct answer is less than fourteen inches!

      Is “lots” somewhere between 1/4 inch and 14 inches? Maybe your guess/answer might need to be a little more precise? See Larry’s answer for precision.

  2. Larry says:

    Answer: 2.63 inches of rain
    Solution coming after prize award.
    Merry Christmas and Happy New Year

    • Brenda says:

      I knew I could count on you for a carefully calculated response!

      Prize announcement as soon as I take a picture of it 😉

      Merry Christmas!

      • Larry says:

        A good engineer always evaluates his solutions from different view points. I did and found that I forgot a factor. The new correct answer (assuming the water trough is level, the trough is not bulging, there is no strong wind from the south, the cows do not disturb the water during the fill time, and the rain covers the whole area unlike Florida where it can rain on one side of the road and not the other) is:
        2.35 inches of rain.

  3. Tammie and Mark says:

    Sounds like Larry knows what he is talking about, but I will put Mark on it

    • Tammie and Mark says:

      I believe that Larry is working with faulty data. We need to know the area of the roof, not the building. And I don’t think he is allowing for time of precipitation occurrence. ( cows drink more during the day). Mark

      • Brenda says:

        Oh my, you all are way to scientific for me! My method was wait til it rains then see how full it is 😉

        Let’s see if I can help at all with further information: I have no idea what the area of the roof is, the water trough is not level (it is sloped to the east to drain down the hill when it overflows), the trough was bulging a little on one side when it was full but Rick put a strap on it and it is pretty straight now, the cows (actually heifers) drink mostly during the day but I have seen them drink in the evening after they eat a lot of hay, when it rains here it is the whole area at least down to Concrete, and just in case this is pertinent in some way, adult cattle drink an average of eight gallons of water per head per day.

  4. Michael says:

    After reading the other possible solutions and doing a great deal of scientific thought and research, I have concluded that it will take 3.25 inches to fill the trough.

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