A loan of money is to be repaid in 7 yearly instalments that increase uniformly and form an arithmetic progression. The first instalment is Rs 5000 and the last instalment is Rs 17000.
(i) Calculate the annual increase between successive instalments.
(ii) Determine the total amount repaid over the entire period of 7 years.
(iii) After how many complete instalments will the borrower have repaid at least half of the total amount found in part (ii)? Justify your answer with appropriate calculations.