For a constant collector-emitter voltage of $8 \mathrm{~V}, the collector current of a transistor reached to the value of 6 \mathrm{~mA} from 4 \mathrm{~mA}, whereas base current changed from 20 \,\mu \mathrm{A} to 25 \,\mu \mathrm{A}$ value. If transistor is in active state, small signal current gain (current amplification factor) will be :