All people living in a city are entitled to a card after they reach the age of 65, guaranteeing them a discount on most of the city's public transport services. A 1990 census record showed that there were 2,450 residents in the city. He reached the age of 64, but in 1991, more than 3,000 people applied for and reasonably received a discount card. Therefore, it is clear that the population growth of the city from 1990 to 1991 must be partly due to people in their sixties Immigration of the city. The assumptions discussed above are based on:. ["Problems with the city's 1990 census record.", "The city's total population grew by more than 500 people during 1990.", 'The person who applied for and received the discount card in 1991 had the right to apply for the card for the first time in that year.', 'None of those 65 years or older who moved to the city in 1991 have not applied for a discount card.']