All day efficiency: PE Power Electric Power Devices practice question

A 500 kVA, 12.47 kV–480Y/277 V pad-mounted transformer (impedance 5.75%), installed in the late 1990s, serves an office building. Its no-load loss is 1.2 kW and its winding loss at rated load is 5.0 kW. The transformer stays energized around the clock, and the building's daily load cycle is:

• 6 h at 450 kVA, 0.90 power factor lagging
• 10 h at 250 kVA, 0.85 power factor lagging
• 8 h with the secondary breaker open (no load)

To compute the all-day efficiency, the energy lost in the transformer over one day is needed. That daily energy loss is most nearly: