A firm works on the activity "delivery of packets to customers". The following information is given. Total Number Weight of all packets Volume Business year activity cost of all packets of all packets...

Extracted text: A firm works on the activity "delivery of packets to customers". The following information is given. Total Number Weight of all packets Volume Business year activity cost of all packets of all packets 2019 123,411 € 8,430 68,470 kg 4,000 m? 2020 135,800 € 9,000 70,000 kg 4,400 m3 The firm's managers are surprised, as the activity cost increased by 10%, while the number of packets increased by only 7%. a) What might, in this case, be the main cost driver for the increase in activity cost? Please give a reason for your answer. b) Based on your answer to question a, what is the corresponding activity-cost rate?