Explanation:
The formula for the standard error of a proportion is:
SE = sqrt((p*(1-p))/n)
where p is the sample proportion and n is the sample size.
To find p, we need to first calculate the proportion of people who smoke regularly:
p = 71/635 = 0.1118
Now we can plug in the values for p and n:
SE = sqrt((0.1118*(1-0.1118))/635) = 0.0194
Therefore, the standard error for the sample proportion is 0.0194.