How old should a child be to buy a train ticket?

The Ministry of Railways of my country stipulates that every passenger who buys a ticket and takes a train has an independent seat, so children's tickets for bullet trains have seats. Child passengers can enjoy child ticket discounts only if their height is within the range of 1.2 meters and 1.5 meters. Secondly, if the child's height is less than 1.2 meters, according to regulations, children under 1.2 meters do not need to buy a ticket, and can ride for free with adult passengers. However, parents and passengers need to note that children under 1.2 meters ride for free, do not need to buy a ticket and therefore do not have an independent seat, and can only ride with accompanying adults. Finally, minors under the age of 16, if their height is more than 1.5 meters, must purchase a full-price train ticket with a real name to ride the train, and they do not enjoy discounts for children's tickets. Thereby this type passenger also has independent seat. <br/>Children with a height of 1.2-1.5m traveling with adults can enjoy half-price tickets, express tickets and air-conditioned tickets (referred to as children's tickets). If you exceed 1.5m, you should buy a full-price ticket. Each adult passenger can carry one child whose height is less than 1.2m free of charge. If there is more than one child, the excess number should buy a child ticket. <br/>Notes:<br/>According to the regulations of the railway department, children are not allowed to purchase tickets for travel alone, and children's tickets must be purchased together with adult tickets. When buying a children's train ticket, you must provide the child's valid ID card information. You can use the child's ID card or household registration book. If the child does not have an ID card, you can use the valid identity information of the accompanying adult.

Children whose height is between 1.2 meters and 1.5 meters enjoy discounts on child tickets. Students over 1.5 meters need to buy student tickets (limited) or adult tickets. <br/>Children who are under 1.2 meters in height and do not need to buy a ticket can ride for free with adult passengers without a seat. Each adult passenger can only bring one free-ticket child.