I have read the brochure and it says there is a wide age range of people.
Since everyone is travelling alone - we are all in the same boat.
I have just booked China or September - I worried like you did but I thought to myself that The worse that can happen is no-one will talk to me and since there are quite a few people who travel this is so unlikey.
If you read some of the other threads you will notice that alot of people are staying in touch after their tours and they state how well everyone gets on together.
It doesnt matter if you are the oldest or youngest. Age is just a state of mind 😉 I am 40