Question 1135862
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Let N be the set of positive integers between 1 and 200, inclusively.

So, N contains exactly 200 elements.



Let F be the set of positive integers from 1 to 200 inclusively that are divisible by 5.


The number of such integers is  {{{200/5}}} = 40;  so the number of elements in the set F is 40.



Of this set F, exactly HALF of its elements are even: in other words, in the set F 20 elements are even.



The problem asks: If the randomly chosen integer from N belongs to F, what is the probability that it is even.



Since exactly half of all elements of F are even, the answer to this question is obvious:  this probability is  {{{1/2}}}.
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 Answered and solved.