Answer:
0.5 Ohms
Explanation:
We note that the node Q is also between the resistors of 1ohm and 2ohms.
We note that the node P is also between the resistors of 2ohms and 3ohms.
Thus, all these resistors are in parallel, beween nodes P and Q
1/Re=1/R1+1/R2+1/R3
1/Re=1/1+1/2+1/3=(6+3+2)/6=11/6 [ohm^(-1)]
Re=6/11=0.54ohms
Rounding to the tenth: Re=0.5 ohms
