Question 1197325
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Five of 10 new buildings in a city violate the building code. A random sample of three {{{highlight(new)}}} buildings
{{{highlight(are)}}} selected for inspection.
a) What is the probability of none of the buildings violate the building code in a sample of 3 buildings

b) What is the probability of at least one of the new buildings violate the building code in a sample of 3 buildings?
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The solution of two other tutors is correct, if these 10 buildings are all new buildings in the city, 

and there are no other new buildings in the city.


But an opposite assumption can be made, too, that the number of new buildings in the city is very large, 
for example, that there are 10,000 new buildings in the city.


Then the condition simply means that the probability that a randomly selected  new building in the city violates the code is 1/2 = 0.5.


Then the problem allows and requires different treatment: it can be considered as a standard binomial distribution problem.



From the problem's formulation, it is impossible to determine which one of the two possible treatments is preferable, 
so the condition is AMBIGUOUS.