Educational note: when histograms are filled, it's typical that a given bin contains entries that are greater than or equal to the lower bin boundary and less then (but not equal to!) the upper bin boundary. I've adjusted the mass window to reflect that (even though admittedly the problem statement was vague on this point).
Educational note: when histograms are filled, it's typical that a given bin contains entries that are greater than or equal to the lower bin boundary and less then (but not equal to!) the upper bin boundary. I've adjusted the mass window to reflect that (even though admittedly the problem statement was vague on this point).