In 1920, it was reported that there were 60 billion barrels of oil in the world oil reserves and we were using 6 billion barrels per year. Given this data, the world should have run out of oil in ten years. However, more recent data suggests that there are currently 1.7 trillion barrels of oil in the world oil reserves and that we are using 34 billion barrels of oil every year. Given that petroleum reserves are a non-renewable resource, how do explain the fact that the world has not run out of oil when it was supposed to over 80 years ago

Employees at a library check out books to patrons. books have an isbn and a name. the library sometimes has multiple copies of the same book. books have one or more authors. a patron is an individual who has an active (non-expired) library card. for each library card, we store the person's first and last names and their address. for each employee, we store their employee id, current salary, first and last name and their address. we also store the employee id of their current manager. each time we check out a book to a patron we need to store the date of the transaction, the employee who checked out the book to the patron, and the library card of the patron. some employees have library cards. if an employee patron turns in a book late, the fine that they pay is a percentage of their salary. some employees are authors who have library cards—they are allowed to check out as many books as they like.