.
Since the solution by Edwin is INCORRECT (unfortunately),
I came to provide the correct solution.
The probability to win $600 is ;
the probability to win $400 is ;
the probability to lose $100 is .
Mathematical expectation is = = = 216.6666666.....
It means that in EACH game you may expect to win 216.67 dollars as your winning prize.
More precisely, it means, that if you play this game many times, your averaged winning sum
will be about 216.67 dollars.
In turn, it means that in 10 games you may expect to win 10 times this value, i.e $2,166.67.
Again, in 10 games you may accumulate 2,166.67 dollars as your winning prize, in total.
In wording form TWO THOUSAND one hundred sixty six dollars and 67 cents.
Now turn on your mind and compare it with $1000.
Note, that it is not my advise for you to follow it in real life (and do not consider it as my advise, please (!) )
I am not responsible for the consequences (!) (!) (!)
It is the solution of the given Math problem ONLY.