Aparallel dc circuit has a total current of 4 amperes and a resistance of .5 ohms. if the current is doubled, and the resistance is halved, how many times more is the new power compared to the old power?

The answer is 2 times.

In parallel DC circuit the power (P) can be calculated by using the values of total current (I) and resistance (R):
P = I²R

The old power is:
Po = Io² x Ro
Io = 4 A
Ro = 0.5 ohms (Ω)
So, Po = 4² A x 0.5 Ω = 8 W

The new power is:
Pn = In² x Rn
In = 4 A x 2 = 8 A
Rn = 0.5 Ω ÷ 2 = 0.25 Ω
So, Po = 8² A x 0.25 Ω = 16 W

Pn ÷ Po = 16 W ÷ 8 W = 2
Thus, the new power is 2 x higher than the old power.

Iam not sure but to me it with be a or dsorry if i was late! hope this ! : )if you really want me to find out the answer that is correct tell me and i will do more research but the a or d makes sense to me.