AC bill cost me more than my housemates

So last month, i started renting in a small room which have AC. I only used it twice. First during the first day and second is during the last 2 weeks of the month, both were turned on less than 5 hours. It costs me RM30. I asked my housemates, they all use more than 5 hours and the one with 4 times only pay for RM20, while the one who used everyday at night costs RM70+. Am i being scammed or is there something i should know??

The rate being charge is RM0.60 / kwh btw

Edit: i was charged with 50kwh. The model is Midea, 1hp, inverter. I used dry mode with 24c in auto fan speed. Everyone has their own separate bills. We did not share.