The equivalent resistance of the three resistors when connected in parallel is:
Since the three resistors in this problem are identical, we can call R their resistance, and we can rewrite the previous equation as
And since we know the value of the equivalent resistance, , we can find the value of R:
Now the problem asks us what is the equivalent resistance of the three resistors when they are connected in series. In this case, the equivalent resistance is just the sum of the three resistances, so