To solve this problem you must apply the proccedure shown below:
1. You have that $50 is added to the prize money each time a caller answers the contest question incorrectly and the first caller has a chance to win $100.
2. Therefore, the amount the 10th caller receives, if the this caller answers the question correctly, is:
x: the amount the 10th caller receives.
y: the number of caller
x=100+50(y-1)
As y=10 (the 10th caller), you have:
x=100+50(10-1)
x=100+50(9)
x=100+450
x=$550