+0
Take the following sentences:

1. Three scoops of ice cream weren't enough.
2. Three scoops of ice cream wasn't enough.
3. That amount of ice cream wasn't enough.

The grammar I have studied says 1 is correct and 2 is wrong. However, if we look at sentence 2 in context of grouping, can we use it?

If we cannot use it, then how do you indicate a grouping (in this case, a grouping of 3 scoops) as opposed to referring to 3 individual items (in this case, 3 individual scoops).

Example: 12 eggs / dozen
+0
JadariteTake the following sentences:

1. Three scoops of ice cream weren't enough.
2. Three scoops of ice cream wasn't enough.
3. That amount of ice cream wasn't enough.

The grammar I have studied says 1 is correct and 2 is wrong. However, if we look at sentence 2 in context of grouping, can we use it?

Yes, for grouping you can use it.
Comments  
JadariteTake the following sentences:

1. Three scoops (plural noun) of ice cream weren't (plural verb) enough.
2. Three scoops of ice cream wasn't enough.
3. That amount of ice cream wasn't enough.

#1 is correct. 'Three scoops ... weren't enough.
 Marius Hancu's reply was promoted to an answer.