Problem: a circular plate with a diameter of 10 inches is kept on another plate of 12 inches diameter . what fraction of the big plate ' s surface is not covered by the small plate ? 
Options: ['a ) 11 / 36', 'b ) 23 / 10', 'c ) 5 / 14', 'd ) 22 / 11', 'e ) 3 / 4']
a