Three resistances of values and are to be connected to produce an effective resistance of This can be done by connecting 

a) 
resistance in series with the parallel combination of and 
b) 
resistance in series with the parallel combination of and 
c) 
resistance in series with the parallel combination of and 
d) 
resistance in parallel with the parallel combination of and 
Three resistances of values and are to be connected to produce an effective resistance of This can be done by connecting 

a) 
resistance in series with the parallel combination of and 
b) 
resistance in series with the parallel combination of and 
c) 
resistance in series with the parallel combination of and 
d) 
resistance in parallel with the parallel combination of and 
(c) These questions are done by hit and trial method only. You check all the options one by one till you get the final desired result 