Bpp kit question

Hello sir there is is this question in bpp kit A CO it is costing question . In one part it asked to calculate contribution per limiting factor . Time was given in minutes both the available hours and per unit required for product .
I calculated it by diving contribution per unit / time per limiting factor in ( hours) I converted given minutes into hours but in solution they took in minutes hence my answer was different.
What are we supposed to take hours or minutes ? And also in throughoutput return we take hours as well