An npn transistor in a common emitter mode is used as a simple voltage – amplifier with a collector current of 4 mA. The terminal of 8 V battery is connected to the collector through a load resistance RL and base through load resistance  RB. The collector emitter voltage VCE=4V , base emitter voltage VBE=0.6V and current amplification factor   β= 100. Find RB (in ohm).