(Scholastic Aptitude Test) $\newline$ If all pelicans have enormous beaks, which of the following must be true? $\newline$ All birds that do not have enormous beaks are not pelicans. $\newline$ No birds that have enormous beaks are not pelicans. $\newline$ All birds that are not pelicans do not have enormous beaks. $\newline$ All birds with enormous beaks are pelicans.

Full solution

Q. (Scholastic Aptitude Test)

\newline

If all pelicans have enormous beaks, which of the following must be true?

\newline

All birds that do not have enormous beaks are not pelicans.

\newline

No birds that have enormous beaks are not pelicans.

\newline

All birds that are not pelicans do not have enormous beaks.

\newline

All birds with enormous beaks are pelicans.

Identify logical implication: Identify the logical implication of the given statement: If all pelicans have enormous beaks, then having an enormous beak is a necessary condition for being a pelican, but not sufficient on its own to determine if a bird is a pelican.
Analyze first option: Analyze the first option: ＂All birds that do not have enormous beaks are not pelicans.＂ This is true because if a bird doesn't have an enormous beak, it cannot be a pelican since all pelicans must have enormous beaks.
Analyze second option: Analyze the second option: ＂No birds that have enormous beaks are not pelicans.＂ This statement is false because having an enormous beak doesn't guarantee the bird is a pelican; other birds might also have enormous beaks.
Analyze third option: Analyze the third option: ＂All birds that are not pelicans do not have enormous beaks.＂ This statement is false because it's possible for non-pelican birds to have enormous beaks too.
Analyze fourth option: Analyze the fourth option: ＂All birds with enormous beaks are pelicans.＂ This statement is also false for the same reason as the second and third options; other birds could have enormous beaks too.