Power dissipated across any resistance is given by

now it is given that when one resistance of value 3 ohm connected the power dissipated is 4 Watt
now another identical resistance of same value is connected then the current will reduce to half of its initial value.
now power across any one resistance is given by

So now we will have

So now the power will become 1/4 times of initial power
So now the power will be
