What is the average height of n people in the group?

[Guest]

Source: Gmatprep2

What is the average height of n people in the group?
1) the avg height of n/3 tallest people in the group is 6 feet 2 1/2 inch and the avg height of the rest of people in grp is 5 feet 10 inch
2) the sum of heights of n people is 178 feet 9 inches.

Ans--A

[Saurav]

What is the average height of n people in the group?

Average Height = Sum of all heights (unknown) / number of people (=n, known)

1) the avg height of n/3 tallest people in the group is 6 feet 2 1/2 inch and the avg height of the rest of people in grp is 5 feet 10 inch

total height = (n/3) * 6-1/2 in + (n-n/3) * 5-10 in

average height =

[ (n/3) * 6-1/2 in + (n-n/3) * 5-10 in ] / n
[ (1/3) * 6-1/2 in + (2/3) * 5-10 in ]

Sufficient

2) the sum of heights of n people is 178 feet 9 inches.

average height = 178-9in / n
Not Sufficient since value of n is unknown

[RonPurewal]

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