Normalising only part of a dataset

[Pardis]

Hello,

I have a dataset with different rock samples, the values for the 10 major elements in each rock are listed by wt. %

I am supposed to only normalise 2 specific values out of the 10 given in each sample so the total of the major elements comes to 100%. Right now most of the totals are either slightly below or above 100%.


Say the sum of values 1:10 adds up to 98.7%, how do I go about only normalising values 1 and 2 to get the total to 100?


This has been doing my head in for about a week now and I am hoping that there is a straight forward solution that I'm just too confused to see. Hoping someone can help me with this.

Thank you!

[alansidman]

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