GMAT Problem Solving (PS) | The average (arithmetic mean) of four packages is 15 pounds. If the we

Since the average of 4 packages is 15, the sum of the packages must be 60.
It has been given that the package must be in the ratio x:2x:4x:8x
We can compute the weights to be 4,8,12,16.

Looking at the answer options, only Option D is not a multiple of 4
(and the sum must be a multiple of 4) and is our correct answer!

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