(20 pts) Consider the bridge circuit shown below where the output voltage Vo is measured by a multimeter. A platinum resistance thermometer whose resistance value at 20C is 500 and sensitivity is 5/C is inserted to the bridge from Ru position. R1=500,R2=515 ,R3=480, the variable resistance R5=100 and Vs=5V. i. Determine the ratio Ra/Rb such that at 25C the bridge is null-type. ii. Determine the Thevenin equivalent circuit between nodes B and D. iii. Determine the output voltage, if the internal resistance of multimeter is Rm=1k