Correct Answer - Option 3 : 45.33 Hz
A power system has two generators having powers P1 and P2
P1 = 50 (50 - f)
P2 = 100 (51 - f)
Given total load, PT = 800 MW
PT = P1 + P2
PT = 50(50 - f) + 100(51 - f)
⇒ 800 = 50(50 - f) + 100(51 - f)
⇒ 800 = 2500 - 50f + 5100 - 100f
⇒ 150f = 6800
⇒ f = 45.33 Hz