Analytical chem
posted by Hannah .
SPECTROPHOTOMETRIC ANALYSIS OF STEEL
I have a known molarity of KMnO4 solution. It was diluted by a factor of 20. Its absorbance is now 1.18. The length of the path is 1 cm.What is the molarity of the new solution.

I think you need the molar absorptivity to solve, and I am not sure that the number that I supplied is the correct number. Chemistry research articles will report different numbers for it, and I know that it is not in CRC handbook. That is why Dr. Bob222 hasn't responded.
Use the following equation:
A=ebc
Where
e=molar absorptivity=1.80 x 104 M1cm1
b=length of cuvette
c=concentration (Molarity)
A=absorbance
Plug and Chug
A/eb=c 
I apologize, this may be why he hasn't responded.

I may be missing something but if you have a "known molarity" of KMnO4, then it's new concn is just M x 1/20 = ?

I goofed on the "English" part of my answer. It's should be its.