It doesn't take long to check.  You can do it in your head,
keeping track with your fingers, thinking through it like this:

On the 1st hour, 125 tickets were sold.
On the 2nd hour, 250 tickets were sold.
On the 3rd hour, 500 tickets were sold.
On the 4th hour, 1000 tickets were sold.
On the 5th hour, 2000 tickets were sold.
On the 6th hour, 4000 tickets were sold.
On the 7th hour, 8000 tickets were sold.
On the 8th hour, 16000 tickets were sold.
On the 9th hour, 32000 tickets were sold.
On the 10th hour, 64000 tickets were sold.

But it's a matter of concern here that the word 
"AFTER" does not mean the the same as the word "ON" 
technically. You should point this out to your teacher.  
It's bad wording.  For technically, if taken literally,
the answer could be in the millions, for it would depend
on how long AFTER 10 hours the doubling continues.

Sorry for opening up a can of worms, but I do think
teachers and textbook authors should be careful with
their wording.  What is taught in mathematics courses 
should agree with what is taught in English courses.
 
Edwin