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weighted averages i

mike mcgarry
lesson by mike mcgarry
magoosh expert
summary
the content provides a comprehensive guide on solving weighted average problems on the gre, highlighting two primary approaches: using sums and considering proportions.
  • weighted averages require combining the averages of two or more groups to find a collective average.
  • the sums approach involves multiplying the average of each group by the number of items in that group, then adding these sums together to find the total sum, which is then divided by the total number of items.
  • the proportions approach is used when groups are defined by percentages or proportions of the whole, multiplying each group's average by its proportion, then adding these products to find the overall average.
  • practical examples illustrate how to apply these methods to solve problems effectively, emphasizing the importance of ensuring the final average falls between the averages of the groups involved.
  • the content underscores the necessity of converting percentages to decimals when using the proportions method.
chapters
00:00
introduction to weighted averages
00:44
the sums approach
03:18
the proportions approach