A 29.8 mL solution of HBr of unknown concentration was titrated using 0.4685 mol L-1 NaOH using phenolphthalein
as a pH indicator. At the moment when the solution turned a consistent light pink colour, the burette volume read 18.84 mL. The initial burette reading before the experiment was 6.66 mL. What was the concentration of HBr in the original HBr solution ?