Answer:
[a]. check attachment. 
[b]. It can not be said that the difference is ascribed to chance as P-value = 0.001 which is less than <<0.05. That is  P-value = 0.001 <<0.05.
Step-by-step explanation:
Without mincing words let's dive straight into the solution to the question above. 
[a]. The drawing showing the histogram of bacterial endotoxin levels is given in the attached picture. 
KINDLY NOTE: The data is right-skewed. 
[b].  ALLERGIC             MEAN        SE MEAN         STDEV           N
       FALSE                     1510             251                  1789            251
         TRUE                    530              109                 343               10
False - true = difference in a. 
Hence, 80 = estimated difference. 
For the difference, 95% CI = (434, 1527). 
DF = 58, P-value = 0.001, and the T value = 3.59. 
Therefore, It can not be said that the difference is ascribed to chance as P-value = 0.001 which is less than <<0.05. That is  P-value = 0.001 <<0.05.