Can anyone help in answering this question pls

- Assume there are 400 athletes in a training camp, who are required to attend the morning drill starting at 4 am. The attendance in morning drills is 70%, i.e. on an average, 280 athletes are present. Fifty new athletes are admitted in this batch.

a. What is the probability of attendance being at least 70% among the new athletes, thus ensuring the overall attendance does not fall below 70%?

b. The training coach thinks that this probability will increase, if the new batch size is 40 instead of 50 students. Is he right in assuming so?