I found this sentence in a dictionary:
The tenuous link between interest rates and investment.
Why is interest rates plural here but investment not? I know investment is a countable noun, so shouldn't it be investments (or both just use singular nouns with no article, like interest rate and investment) in order to match before and after and?
Best Answer
This is correct because interest rates are values that change over time. Also there are various rates for different products.
In this interpretation, investment would be an activity (like running), not a thing, so you don't make it plural.
You could say:
But in this case, investments refers to those specific investment products (like a savings account and some stocks) where there can be more than one.
More context is needed to know which option is correct.