I part of the question In a peripheral blood smear an averag

I part of the question

In a peripheral blood smear, an average number of 3 lymphocytes is expected.

Calculate the probability that the experimentally–measured number of lymphocytes is 2.

Solution

Note that the probability of x successes out of n trials is          
          
P(x) = u^x e^(-u) / x!          
          
where          
          
u = the mean number of successes =    3      
          
x = the number of successes =    2      
          
Thus, the probability is          
          
P (    2   ) =    0.224041808 [ANSWER]