Answer: Sale of newspaper in a convenience store is more variable.
Explanation:
For variability or consistency , we use the method of coefficient of variation, which states that

So for sale of newspaper in an airport newsstand is given by

Similarly, for sale of newspaper in a convenience store is given by

Since we get that the sale of newspaper in a convenience store is more than the sale of newspaper in an airport newsstand.
So, Sale of newspaper in a convenience store is more variable.