1. Calculate the total resistance between X and Y in these circuits:

2. In a science lesson, a student is given three 1.2 kΩ resistors.

What is the lowest possible resistance that the student could achieve by combining these resistors in to a circuit?

3. In another science lesson, a student is given five 40 Ω resistors.

Show how the student could combine all five resistors so that the total resistance of the circuit is: