A factory’s power consumption P(t), in kilowatts, was first measured 0.5 hours after start-up and then at the times listed.
t (h): 0.5 1.2 2.0 3.0
P(t) (kW): 0.8 1.0 0.9 0.7
Assume (i) power increases linearly from 0 kW at t=0 to 0.8 kW at t=0.5 h and (ii) between subsequent measurements it continues to change linearly. Approximate the total electrical energy used, in kilowatt-hours, during the first 3 hours of operation.