The MGM Grand Theme Park plans to sell admittance tickets in advance and restrict the number of people inside at one time in hopes of limiting long lines often found at such parks.“You can have a great theme park, but people won’t have a good time if they spend all day in line,” said Tom Bruny, MGM Grand spokesman. “When you go places like that, you leave mad.” Bruny said the unconventional approach of selling a limited number of tickets in advance could mean sellouts on some days, causing walk-up customers to be denied entry. Most theme parks allow unlimited numbers inside, but MGM Grand will allow no more than 8,000 people inside at one time, Bruny said. People who enter can stay all day. The advance ticketing should make the visit more enjoyable and allow guests to plan ahead, Bruny said. The 33-acre park will haveseven rides, four shows, eight themed areas and dining areas. Tickets for the theme park will go on sale tomorrow, by telephone, Bruny said. People also can buy tickets at the gate after opening, but they are not guaranteed entry that day. Adult and teen tickets will cost $ 25. Tickets for children ages 4 to 12 will cost $ 20. Children 4 and under will be admitted free. This winter, the park will be open from 10 a.m. to 6 p.m. daily. In the spring, it will be stay open until 10 p.m. and in the summer until 1 a.m.