Answer:
The answer is 100%.
Step-by-step explanation:
Over booking is a pretty common practice throughout the hospitality sector and most services.
If the stated 5% of the guests not showing up rule applies over the 210 reservations, this means that 10,5 people of those 210 will not show up to claim their rooms in which case all 200 rooms in the hotel will given to the arriving costumers.
So the probability that all guests who arrive will receive a room is 100%.
I hope this answer helps.