One adult and 10 children are in an elevator.
If the adult's weight is 4 times the average (arithmetic mean)
weight of the children, then the adult's weight is what fraction
of the total weight of the 11 people in the elevator?
Im not really sure if i interpreted the question right but this is one way you could solve it,
represent weight of adult by variable A
represent the average weight of a child as variable C
We are told that A = 4C
The total weight in the elevator (10 children and 1 adult) is therefore
= 14 C
The adults fraction of the total weight of the lift is then
4C/14C, variable Cs cancel and your left with the adults weight as a
fraction of 2/7 of the entire lift weight
hope that helps