Power is the rate of work done given by dividing work done by time.Efficiency is the ratio of work output to work input
power input= 100 watts
power output = x
efficiency= 0.8
thus 0.8 = x/100, therefore x = 80
power is given by energy times time
hence time = 80/300000 = 0.00026 seconds
Time in hours = 0.00026/360 = 7.407 x 10 ∧7 hours