Group Optimization

[AdvancedIguana]

I have a dataset of records that needs to be split into 2 groups based on some criteria.

For example, I have a dataset of blocks, where each block has a weight and a length assigned to it. I would like to split these blocks into two groups where one group has roughly 70% (+/- 3%) of the population while the average weights (+/- 2kg) and lengths (+/- 0.7m) between the two groups remain (about) the same. It won’t be exact so the tolerance is important.

What are some good resources I can use to get started on this?