Proofreading Mistakes
If proofreader 
finds 
mistakes and proofreader 
finds 
mistakes, 
of which were also found by , how manymistakes were missed by both and ? Assume there are a total of 
mistakes, so proofreader finds a Fraction
of all mistakes, and also a Fraction 
of the mistakes found by . Assuming these fractions are the same,then solving for gives
The number of mistakes missed by both is therefore approximately
References
Pólya, G. ``Probabilities in Proofreading.'' Amer. Math. Monthly, 83, 42, 1976.
- Nonagon
- Nonagonal Number
- Nonagram
- Nonassociative Algebra
- Nonassociative Product
- Nonaveraging Sequence
- Noncentral Distribution
- Noncommutative Group
- Nonconformal Mapping
- Nonconstructive Proof
- Noncototient
- Noncylindrical Ruled Surface
- Nondecreasing Function
- Nondividing Set
- Nonessential Singularity
- Non-Euclidean Geometry
- Nonillion
- Nonincreasing Function
- Nonlinear Least Squares Fitting
- Nonnegative
- Nonnegative Integer
- Nonnegative Partial Sum
- Nonorientable Surface
- Nonpositive
- Nonsquarefree