Answer: 3.41
Step-by-step explanation:
Given : In a recent survey found that 25.9% of all adults over 70 wear glasses for driving.
i..e Proportion of adults over 70 wear glasses for driving : p= 25.9%=0.259
Sample size : n= 81
Now , the formula to find the standard deviation : [tex]\sigma=\sqrt{np(1-p)}[/tex]
Then , the standard deviation of the number who wear glasses would be :
[tex]\sigma=\sqrt{81(0.259)(1-0.259)}=\sqrt{81(0.259)(0.741)}\\\\=\sqrt{15.545439}=3.94277047265\approx3.94[/tex]
Hence, the standard deviation of the number who wear glasses = 3.41 .
