The power of the bulb is P = RV2 Therefore, 100 = R100V2 ⇒ R1001 = V2100 where R100 is the resistance (at any temperature) corresponds to 100 W. Similarly, 60 = R60V2 ⇒ R601 = V260 and 40 = R40V2 ⇒ R401 = V240 From these equations, we get P100 > P60 > P40 ⇒ R1001 > R401 > R601