[age] or [ages] of the youngest and oldest ,,,,

Suppose that you are taking an English course made for new immigrants who need to improve their basic English skills. There are about fifty students in your class. You have a question for one of your classmates, as shown below.

(1) What is the age of the youngest and oldest students in our class?

My non-native English speaking friends revised the sentence to make (2) below.

(2) What are the ages of the youngest and oldest students in our class?

A possible answer is " The youngest one is twenty, and the oldest one is forty-two."

I chose to use the singular form of "age" because there is only one age for being the youngest and for being the oldest.

Who is correct? Thank you very much for your help and time.