Subject verb agreement for "A greater number of"

What is the subject-verb agreement for the phrase "A greater number of"?

I came across this sentence and am confused.

A greater number of cycles with paracetamol is associated with increased risk of ...

Solution 1:

It could be either, depending on whether you're looking at 'one' greater number of things, or looking through it to the 'greater number' of them.

• A greater number of students have phones now.
• A greater number of cycles per second requires a faster reaction time.

In your example, use is if the association is with the increased number of cycles (it's saying that since there are more cycles, risk has also increased). If you're saying that more of those cycles are associated with the increased risk - that is, the association is between the cycles and the risks, use are (it's saying that more of the cycles are associated with increased risk).