In finding this value you average lower and upper bound
(0.6+0.82)/2 = 0.71
=0.71 estimated
margin of error = distance from estimate point lower/ upper bound
This interval will be twice margin error
(0.82-0.6)/2 = 0.11
How far is 0.82 from 0.71 ??
=0.11=11%
Formula for mid point.
(x1/2+x2/2 , y1/2+ y2/2)
Mid point=
(1/2+ (-3)/2 , 4/2+ 7/2)
(-2/2 , 11/2)
(-1, 5.5)