Singular or plural noun when referring to two groups

I have problems deciding whether I should use singular or plural nouns. For example, which of the following sentences is correct?:

(...) to draw a size comparison between the nose of old and young people (...)

(...) to draw a size comparison between the noses of old and young people (...)

The difficulty arises from the fact that each person only has one nose. When many people are involved, there are noses, one for each individual. If I use nose, I am neglecting the fact that there is a group of noses (those of old and young people), but if I use noses, one could think that a single person may have more than one nose.

Thanks.

Solution 1:

When referring to multiple individuals or groups, you usually (check answer linked in Edwin Ashworth's comment down below) go with the plural form of the noun that is common to all the individuals or groups. Thus, "noses" would be grammatically correct.