four resistors of four ohm each are connected in parallel , four such combination are then connected in series. what will be the total resistance?

We can first simplify the circuit to find the equivalent resistance in the circuit. 

 

First considering, 4 resistances of 4 ohms each connected in parallel. 

 

1/R'= 1/R1 + 1/R2+ 1/R3+1/R4 = 4* 1/4 = 1

R' = 1 ohm

 

Now, four such blocks of resistances are connected in series

 

Hence, R" = R' + R' + R' +R' = 4* R' = 4 ohms

Hence total resisance in the circuit is 4 ohms.