Average

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Average

by beater » Thu Oct 02, 2008 3:17 pm
What is the ratio of the average (arithmetic mean) height of students in class X to the average height of students in class Y?
(1) The average height of the students in class X is 120 centimeters.
(2) The average height of the students in class X and class Y combined is 126 centimeters.

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by Morgoth » Thu Oct 02, 2008 5:03 pm
Statement (1) & (2) alone are insufficient.

Combining (1) & (2)
avg. X = 120
A/x = 120
A = 120x

Z / (x+y) = 126
Z = 126(x+y)

A=120x
Z = 126(x+y)

unless we know the individual avg. of Y or number of students in X or Y we cannot solve this. Insufficient.

Thus, E.

OA?

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by beater » Thu Oct 02, 2008 8:46 pm
OA - E. Thanks!