text: formula_3 With these definitions the quartiles in the last example are 106, 110 and 115: P("X" ≤ 106) = 1/3 and P("X" ≥ 106) = 7/9; P("X" ≤ 110) = 5/9 and P("X" ≥ 110) = 5/9; and P("X" ≤ 115) = 7/9 and P("X" ≥ 115) = 1/3