Question:
Find a rational number and also an irrational number lying between the numbers 0.3030030003 ... and 0.3010010001 ...
Solution:
Let
$a=0.3030030003 \ldots$
$b=0.3010010001 \ldots$
Here decimal representation of a and b are non-terminating and non-repeating. So a and b are irrational numbers. We observe that in first two decimal place of a and b have the same digit but digit in the third place of their decimal representation is distinct.
Therefore, a > b.
Hence one rational number is $0.3011$ lying between $0.3030030003 \ldots$ and $0.3010010001 \ldots$
And irrational number is $0.3020200200020000 \ldots$ lying between $0.3030030003 \ldots$ and $0.3010010001 \ldots$