Answer:Proportion Of Flags=19.6%
part b: Proportion of flagged returns containing error =91.8%
Step-by-step explanation: The examiner flags the 90% of the erroneous returns so if for example he get 50 erroneous returns he will flag
50*90/100=45
of them
Similarly if he gets 100 correct returns, he will flag
100*2/100=2
of those a/c to the question
So as it is mentioned that the returns he reviews contain 20% erroneous returns so the rest of the returns i.e. 80% will be correct.
Hence he will flag 90% of the erroneous and 2% of the correct ones
[tex]Proportion Of Flags=20\frac{90}{100} +80\frac{2}{100} \\[/tex]
Proportion Of Flags=19.6%
part b
Now we have to find the ratio of erroneous returns flagged to the total number of flags which can be found by
[tex]Proportion2=\frac{20*90/100}{19.6}[/tex]
Proportion2=0.918
in percentage
Proportion2=91.8%