Physics---DC electricity

From the graph, when it is 20*C, the resistance of the thermistor is R = 1.5 kohm = 1500 ohm

The voltage of the power supply, V = 6.0 V

By V = IR

Reading on the milliammeter, I = V/R

= 6.0 / 1500

= 4 X 10^-3 A

= 4 mA