How can three resistors of resistances `2Omega,3Omegaand6Omega` be connected to give a total resistance of a] `4Omega`. b] `1Omega` ?

Explanation

i] If `3Omegaand6Omega` are connected in parallel thus, equivalent resistance of parallel combination = `2Omega`.

If this combination is connected in series with `2Omega` resistance, then total equivalent resistance = `2Omega+2Omega=4Omega`.
ii] Since equivalent resistance is less than the least value of resistance [i.e. `2Omega`], it means that all three resistors are connected in parallel.
Equivalent resistance = `(1/6)/6=1Omega`