A class consists of four students: John, Lisa, Mark, and Nina. The following conditions are given: 1) John is older than Lisa but younger than Mark. 2) Nina is the youngest. 3) Lisa is not the oldest. Who is the oldest student in the class?
A group of animals consists of a lion, a tiger, a bear, and a wolf. The following conditions are given: The lion is heavier than the tiger but lighter than the bear. The wolf is lighter than the tiger. Which animal is the heaviest?