Typographic errors in a text are either nonword errors (as when "the" is typed as "teh") or word errors that result in a

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Typographic errors in a text are either nonword errors (as when
"the" is typed as "teh") or word errors that result in a real but
incorrect word. Spellchecking software will catch nonword errors
but not word errors. Suppose human proofreaders
catch 71.3% of nonword errors. You ask a fellow student
to proofread an essay in which you have deliberately
made 17 nonword errors.
(a) What is the mean number of errors caught?( Keep 1 decimal
place)
=
(b) What is the standard deviation 𝜎 of the number of
errors caught?(keep 2 decimal places)