0 votes 0 votes Let $A=\left \{ \sum _{i=1}^{\infty } \frac{a_{i}}{5^{i}}:a_{i}=0,1,2,3\:or \:4\right \}\subset \mathbb{R}$. Then $A$ is a finite set $A$ is countably infinite $A$ is uncountable but does not contain an open interval $A$ contains an open interval TIFR tifrmaths2016 + – soujanyareddy13 asked Aug 30, 2020 • edited Oct 18, 2020 by soujanyareddy13 soujanyareddy13 198 views answer comment Share Follow See all 0 reply Please log in or register to add a comment.