# Resolved: Fifth question of the practice exam

can Lambda value be considered as the time taken for average number of events in that time interval?

as per the lecture Lambda is frequency of events in a specific time interval. So in that question - why is lambda not equal to avg events in time which is 2 (2 trees every four minutes).

Hey Sandesh,

Thank you for reaching out!

Note that it is important to consider the same time intervals. In the Q&A example in the lecture, the time interval was 1 day:

*Given that you receive 4 questions per day on average, what is the probability of receiving 7 questions today?*

Therefore, lambda = 4.

In the practice exam question, we are told that the average number of trees per **4 minutes** is 2. This makes for 4 trees per **8 minutes** on average. Since the question asks for the probability of of less that 5 trees appearing in **8 minutes**, we need to use lambda = 4.

Hope this helps!

Kind regards,

365 Hristina

Thank you Hristina!