Answer: 
Mrs. O’conner will make 16 batches. 
Step-by-step explanation: 
Given that total 72 people are going to attend the party, and Mrs. O’ conner will prepare 2 batches of banana pudding for every 9 people attending. 
72, when divided in a group of 9 people, it will come = 72/9 = 8 groups 
For a group, she will make batches 
Therefore, 1 group (9 people) = 2 batch 
 8 groups (9*8=72 people) = 8*2 = 16 batches 
Hence, Mrs. O’conner will make 16 batches for 72 people.