IOPS and #of disks Calculations!

Hello,

I would like to know the right way to calculate and chose answers in the exam since it's all over the place when it comes to those type of questions.

Question:

A company plans to deploy a new application in their environment. The new application requires 5 TB of
storage space. During peak workloads, the application is expected to generate 3000 IOPS with a typical
I/O
size of 3 KB. The capacity of each available disk drive is 750 GB. In addition, the maximum number of
IOPS a drive can perform at with a 70% utilization is 90 IOPS.
What is the minimum number of disk drives needed to meet the application’s capacity and performance
requirements for a RAID 0 configuration?

What is the methodology and what would be the answer to chose for the exam and not real life scenario please!?