It can be observed that,
Taxi fare for 1st km = Rs. 15
Taxi fare for first 2 km = 15 + 8 = Rs. 23
Taxi fare for first 3 km = 23 + 8 = Rs. 31
Taxi fare for first 4 km = 31 + 8 = Rs. 39
[1.5 marks]
Clearly 15, 23, 31, 39 … forms an A.P. because every term is 8 more than the preceding term.
[0.5 mark]