At 20 oC, a silicon rod of uniform cross-section is connected to a battery with a terminal

Question:

At 20 oC, a silicon rod of uniform cross-section is connected to a battery with a terminal voltage of 6.0 V and a 0.50-A current results. The temperature of the rod is then increased to 25 oC.
(a) What is its new resistance?
(b) How much current does it carry?
(c) If you wanted to cut the current from its room temperature value of 0.50 A to 0.40 A, at what temperature would the rod have to be?