Power in a lamp is P = I²R

Steps:

• Calculate P_x = (0.5)² × 9 = 0.25 × 9 = 2.25 W
• Calculate P_y = (3)² × 1.2 = 9 × 1.2 = 10.8 W
• Find ratio P_x : P_y = 2.25 / 10.8 ≈ 0.208
• Round to 0.22, matching option A

Why A is correct:

• Ratio 2.25/10.8 = 0.208 rounds to 0.22 using P = I²R formula

Why the others are wrong:

• B: 0.75 from incorrect P = IR (0.5×9 / 3×1.2 = 4.5/6 = 0.75)
• C: 1.3 from misdividing currents or resistances alone
• D: 4.5 inverse ratio P_y / P_x = 10.8 / 2.25

Final answer: A