Exhausted teacher
Level
pending
A teacher takes her class students to a zoo trip.She only takes 3 student at a time,but always different 3 students.if she has to go to the zoo 84 times more than a particular student.How many children are there in her class?
The answer is 10.
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1 solution
See a teacher can choose the different 3 students from x students in xC 3 ways.This will be equal to 84 + {x-1}C 2.This is because the student has to choose only 2 classmates from the remaining x-1 students .(C- combinations)