10 resistors each of resistance 10 Ω can be connected in such as to...

When all the resistors are connected in series, the total resistance is

{R}_\max = 10R

⇒ {R}_\max = 10 \times 10 = 100Ω

When all the resistors are connected in parallel, the total resistance is

{R}_\min = \dfrac{R}{10}

⇒ {R}_\min = \dfrac{10}{10} = 1Ω

Hence, the ratio,

\dfrac{{R}_\max}{{R}_\min} = \dfrac{100Ω}{1Ω} = 100.