Food protein-induced enterocolitis syndrome (FPIES) is an uncommon disorder characterized by an allergic reaction to foo

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Food protein-induced enterocolitis syndrome (FPIES) is an
uncommon disorder characterized by an allergic reaction to food
that affects the gastrointestinal system.
It is estimated that the incidence of FPIES in the USA is
0.34%.
Could you please explain how to find these answers and please do
not use statistic Software! (I need to answer calculations
by hand.)
A. Write down the estimated incidence rate as a decimal
and use this to determine the expected number of cases of FPIES per
1000 people in the USA population.
B. Assuming that the Poisson distribution may be used to model
X, the number of cases of FPIES diagnosed per 1000 people, find the
probabilities (correct to 4 decimal places) that
in a community of 1000 people:
1) there are at most 2 diagnosed cases of
FPIES
2) there are at least 3 diagnosed cases of
FPIES.
C. Determine the mean, variance and standard deviation
of X.