1)
$S = \dfrac{1}{31} + \dfrac{1}{32} + \dfrac{1}{33} + ... + \dfrac{1}{60}$
$S = \left ( \dfrac{1}{31} + \dfrac{1}{32} + ... + \dfrac{1}{40} \right ) + \left ( \dfrac{1}{41} + \dfrac{1}{42} + ... + \dfrac{1}{50} \right ) + \left ( \dfrac{1}{51} + \dfrac{1}{52} + ... + \dfrac{1}{60} \right )$
$\Rightarrow S > \dfrac{1}{40}.10 + \dfrac{1}{50}.10 + \dfrac{1}{60}.10$
$\Rightarrow S > \dfrac{1}{4} + \dfrac{1}{5} + \dfrac{1}{6}$
$\Rightarrow S > \dfrac{3}{5}$
2)
$S = \dfrac{1}{31} + \dfrac{1}{32} + \dfrac{1}{33} + ... + \dfrac{1}{60}$
$S = \left ( \dfrac{1}{31} + \dfrac{1}{32} + ... + \dfrac{1}{40} \right ) + \left ( \dfrac{1}{41} + \dfrac{1}{42} + ... + \dfrac{1}{50} \right ) + \left ( \dfrac{1}{51} + \dfrac{1}{52} + ... + \dfrac{1}{60} \right )$
$\Rightarrow S < \dfrac{1}{31}.10 + \dfrac{1}{41}.10 + \dfrac{1}{51}.10$
$\Rightarrow S < \dfrac{1}{30}.10 + \dfrac{1}{40}.10 + \dfrac{1}{50}.10$
$\Rightarrow S < \dfrac{1}{3} + \dfrac{1}{4} + \dfrac{1}{5} < \dfrac{4}{5}$
$\Rightarrow S < \dfrac{4}{5}$
