The interval given was 33% to 37%
This means that subtracting the margin of error from the percentage of the population that visit the library once a year gives the lower end and adding the margin of error to the percentage of the population that visit the library once a year gives the upper end
Let x denote margin of error and y denotes the percentages of the population that visit the library once a year
we can get the following equations and solve for the values of x and y
[tex]y - x = 33\%.......eqn1 \\ y + x = 37\%........eqn2[/tex]
Adding eqn1 and eqn2 to gives
[tex]2y = 70\% \\ y = 35\%[/tex]
Putting the value of y into any of the equations
[tex]35\% + x = 37\% \\ x = 37\% - 35\% \\ x = 2\%[/tex]
Thus, the margin of error is
[tex] \pm2\%[/tex]
Therefore we enter 2 in the box
