Sum of resistance =9Ω
Connect three resistors of resistance 3Ω in series , the resultant resistance will be 9Ω.
Case 2 :
Resistance = 1Ω
Connect three resistors of 3Ω in Parallels , the resultant resistance will be 1Ω.
Note : when we connect n resistors of equal resistance (R)in parallels , the equivalent resistance is given by Resistance of Resistor/total number of resistors.
here in above case equivalent resistance will be 3/3 = 1Ω
Resultant Resistance = 2Ω
This case is not possible by using three resistors of 3Ω resistance each.
Hope this helps you.
Note : when resistors are connected in Series their resistances add up.