Probably because in the experiment must give solution Orange and hot, and then applies a quarter back as the pink hotel, great place to notice the color at the end. Thus tolerance experiment results.
Probably because of the trials to get a solution to warm orange and then straight back to the tri-pink color gives notice to terminate the uncertainty. The discrepancy results
May be due in the experiment to obtain solutions before and after warm orange then tri nitrate is pink to observe color end point is uncertain. The experimental results are mistaken.