Nice one Jerry. :)

--
HTH :)
Dana DeLouis
Windows XP & Office 2003


"Jerry W. Lewis" wrote in message
...
Another approach to the problem, which avoids Solver altogether, is to
note
that this is a quartic equation in x=exp(-y/2). Quartic equations have
known
solutions
http://en.wikipedia.org/wiki/Quartic_equation
Ferrari's method has a solution with real x0 [so that y=-2*ln(x) is also
real] by taking +/-[s] to be - and +/-[t] to be + to get
x=0.97209229125665744 or y=-2*ln(x)=0.056609058353243358

Jerry

<snip
have to use continuous compounding. Here is the formula with the numbers
inputed and I'll use "Y" as the variable to solve for:

4(EXP-(Y*.5)) +4(EXP-(Y*1))+4(EXP-(Y*1.5))+104(EXP-(Y*2.0))

all of this must equal 104.21 when the equation is solved out.
<snip