Arun joins a monthly saving plan in which each deposit is larger than the previous one by the same fixed amount. His 5th deposit is Rs 600 and his 20th deposit is Rs 1350. Assume the deposits form an arithmetic progression in the order they are made.
(i) Find the amount of his first monthly deposit and the fixed increase between consecutive deposits.
(ii) Calculate the amount of his 25th monthly deposit.
(iii) Find the total amount he will have deposited in the first 25 months.