Two editors, Ed and his boss Ada have just finished the proof-reading of a new book prior to its publication.

Working **independently**, Ed detected 25 errors and Ada ended up only with 19.

Provide your estimate (assume what you may) regarding the quantity of errors still remaining after their inspection.

Spotty Editing is a similar problem to this one, except this time we don't know the total number of errors found.

Let E be the total number of errors in the book and let D be the total number of errors found by both Ada and Ed (this will be between 25 and 44).

Then applying the solution from Spotty Editing yields an initial equation of: E - D = E * (E-19)/E * (E-25)/E

This simplifies to E = 475/(44-D).

If many of the errors found by Ed were also found by Ada (D is close to or exactly 25) then the total number of errors is small. If D=25 then E is 25 implying they found all errors. A little bigger D=27 implies E=28 so then they only missed one error.

But if the errors found by Ed and Ada are largely different then there could be a huge number of errors still around. If D=41 then E=158 which means that they found slighty more than a quarter of the errors. Worst case scenario is Ed and Ada found all different errors with D=44. Then E diverges to infinity and for all we know the entire book could be nothing but errors.

We do need some additional info to make a more substantive claim about the errors that may actually be in the book. Obviously having a value for D would work.

Just a number for the quantity of things checked may offer an alternate approach. 25 errors in a short book of 10000 words is going to be different from 25 errors in a typical novel of 60000-90000 words.