Approximate probability given the mean

Question

So I was given some data of passenger boarding and disembarking numbers for a certain train line (for all the stations in that line).

My question is: Given the mean of disembarking passengers for each station(which was computed with R's summary) is there a way to approximate the probability of a passenger exiting at each station? The constraint is that on the first station, 0 passengers will disembark, whereas on the final station, all the remaining passengers will disembark.

The data look as follows:

data

Trip    Station1    Station2    Station3    Station4 ... StationN
1       0           10          4           70       ... 30
2       0           4           40          10       ... 2
...

summary(data) 
    Station1       Station2      Station3     ...
 Min.   :0       Min.   :0.0   Min.   :0.00    
 1st Qu.:24.25   1st Qu.:0.0   1st Qu.:0.25   
 Median :32.50   Median :1.0   Median :1.00   
 Mean   :36.30   Mean   :0.6   Mean   :0.70
 3rd Qu.:45.75   3rd Qu.:1.0   3rd Qu.:1.00
 Max.   :63.00   Max    :2     Max    :3

The summary results as well as the data are not the actual data.

Answer 1

I believe you can just use the mean of the $i$th station divided by the sum of the means for all stations (including the last station), but I might be misunderstanding the question. Is there a reason my simple answer wouldn't work?