In a database system within a banking application, transaction A is transferring $1000 from account ACC1 to account ACC2. At the same time, transaction B is processing every account record and adding interest payments by increasing each balance by 1.5%. Initially, ACC1 has a balance of $4000 and ACC2 $5000. The following sequence of operations takes place

• What should be the final balance values if the transactions were performed serially? [10]

• What are the actual final values ensuing from the above sequence? [4]

Explain how this error can be avoided?