Explain, in words, why two resistors in parallel always give less resistance than the smaller of…

Step 1. (a) The second resistor has the same voltage across it, so the current in the first does not change, and the second adds some current of its own. More current for the same voltage means a smaller resistance, $R = \dfrac{V}{I}$. Even a huge resistor lets a little current through.

Step 2. (b) $\dfrac{1}{R} = \dfrac{1}{6\ \Omega} + \dfrac{1}{60\ \Omega} = \dfrac{11}{60\ \Omega}$, so $R = 5.45\ \Omega$.