(Q22).In which of the following situations, does the list of numbers involved make an arithmetic progression, and why?

(i) The cost of digging a well, after, every metre of digging, when it costs Rs. 150 for the first metre and rises by Rs. 50 for each subsequent metre.

Cost for digging the first metre = Rs. 150

Cost for digging subsequent metres = Rs. 50 each.

i.e.,

Meters 1 2 3 4 5 .........
Cost 150 150 + = + 50 = + 50 = + 50 =

The list is 150, , , , , ……..

Here d = a2 – a1 = a3 – a2 = a4 – a3 = ……. =

∴ The given situation represents an A.P.