Strategy Guide 3 (5th Ed) - Weighted average

[Harshayes]

Hi there,

I have a basic question since I want to understand this correctly.

This is regarding the weighted average example in 5th edition of strategy guide 3 on pages 56-57.

The problem definition is scattered over a few paragraphs of explanations here. But in summary, it is given that 20 and 30 have weights a and b in the ratio 3:1. And we need to find the weighted average.

But can someone please clarify how 22.5 and 28 are derived ? And what are these values? What does "Simply write the ratio as fraction, and use the Nr and Dr as weights" mean?

Appreciate the help.

Thanks.

[RonPurewal]

Hi,

1/
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2/
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Thanks.