What is the successful rate to get my friend visa approved who is Vietnamese stay in Vietnam planned a personal free and easy tour in shanghai?

What is the successful rate to get my friend visa approved whose is Vietnamese stay in Vietnam planned a personal free and easy tour in shanghai?. If we just provide them all the necessary document such as minimun 6 month valid passport, photo, round trip ticket, hotel booking receipt and complete application form. My concern is i don't wanna waste my air ticket and hotel if my application can't go thru the approval.