A`p-n-p` transistor is used in common-emitter mode in an amplifier circuuit. A change of `40muA` in the base current brings a change of `2mA` in collector current and `0.04V` in base-emitter volatage. Find the
(a) input resistance `r_(i)` and
(b) the base current amplification factor `(beta)`.
(c ) if a load of `6kOmega` is used, then also find the voltage gain of the amplifier.