Here's why:

* Interphase is the period of growth and normal activity: During interphase, cells carry out their typical functions, produce proteins, and prepare for cell division. This phase is crucial for the cell's survival and proper function.

* Mitosis (cell division) is relatively brief: Mitosis, the process of dividing the nucleus and cytoplasm, is a relatively short phase compared to interphase.

* The ratio varies: The exact proportion of time spent in interphase versus mitosis varies depending on the type of cell and its role in the organism. However, in general, cells spend much more time in interphase.

Think of it like this: Imagine you're studying for an exam. You spend most of your time reading and understanding the material (interphase), and then you take the exam (mitosis) which is a relatively short period compared to your study time.