Question 1150992
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From the context, there is one-to-one correspondence between students and drinks.


So, 30 students each have 1 drink, that are of one of 5 kinds.


Hence, there are 5 groups of 6 students each (6 = 30/5), so that every 6 students inside each of 5 groups have the same drink.


<U>ANSWER to the problem's question</U> is  <U>6 people</U>.
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Solved.