Why not write all of the numbers in decimal fraction form, to make them easier to compare?
68 2/3 = 68.666...
72 1/2 = 72.500
68 3/10 = 68.300
74 7/11 = 74.636...
68 1/2 = 68.500
550/8 = 68.750
Now ask yourself: Which of the last four numbers is between 68.666.. and 72.500?
To find the area of a circle find the radius and square it then multiply by PI
Area = PI x r^2
