4 The circumference round the trunk of a large tree is measured and found to be 5.00 m . After one year the circumference is measured again and found to be 5.02 m .
- Given that the circumferences at yearly intervals form an arithmetic progression, find the circumference 20 years after the first measurement.
- Given instead that the circumferences at yearly intervals form a geometric progression, find the circumference 20 years after the first measurement.