Here is the formula set up to solve for MGD (Million Gallons per Day).
=3*936*A21^1.5*1440/1000000
936 is the length in inches.
A21 is a cell with the inches going over the weir.
1440/1000000 is to convert the gallons per minute to MGD.
What I want to do is set up another formula where the desired MGD could be
entered in a cell and the result would be the inches to let flow over the
weir.
(The practical application of all this is to set movable gates on a dam.)

"Rick Rothstein (MVP - VB)" wrote:

Show us the equation you have for calculating flow over a horizontal weir...
there is no way we can help you isolate the "X" in "X^1.5" unless we know
the rest of the equation.

Rick


"Shawn" wrote in message
...
I have a formula for finding the flow over a horizontal weir. ( gpm = 3 *
weir L ins. * overflow ins. 1.5th) I want to set up an Excel formula to
give
the result as the overflow inches. ("X" in "X^1.5") How do I do that?