4 Ebola patients are to be treated with a new serum The prob

4 Ebola patients are to be treated with a new serum. The probability of success with this serum in each patient is 0.4. What is the probability of only 2 successful treatments? Show appropriate formula and calculations.

Solution

Note that the probability of x successes out of n trials is          
          
P(n, x) = nCx p^x (1 - p)^(n - x)          
          
where          
          
n = number of trials =    4      
p = the probability of a success =    0.4      
x = the number of successes =    2      
          
Thus, the probability is          
          
P (    2   ) =    0.3456 [ANSWER]