impossible exercise

So I ama university student, I have to solve this crazy exercise and I have researched everywhere on the internet for help and I have found nothing precise that can help me, or give a hint to solve the whole thing
Here it goes:

We assume that the duration of a fail-safe operation of a computer follows an exponential distribution, ξ∈Ex (λ). Find a meaningful estimate of the parameter λ if we have observations over the duration of a fail-safe 5-computer expiration - 2, 3, 5, 4, and 7 years. What is the expected scatter of the service life

So, is the "expected scatter" the mean of our sample (which is 4.2)?
What is the meaningful estimate"