Answer: 17.89
Step-by-step explanation:
In binomial distribution, the standard deviation is given by :-
[tex]\sigma=\sqrt{np(1-p)}[/tex]
As per given , we have
The number of vouchers in the sample with errors is denoted by x.
p= 0.20 , n = 2000
Then , [tex]\sigma=\sqrt{2000\times(0.2)(1-0.2)}[/tex]
[tex]\sigma=\sqrt{320}=17.88854382\approx17.89[/tex]
Hence, the standard deviation of x is 17.89.