This is NOT a deck. But it is EXTREMELY helpful.
These are statistically the best numbers of a Swamp/Plains deck.
Creatures/Artifacts:
1 mana: 2
2 mana: 6
3 mana: 8
4 mana: 1
5 mana: 2
6+ mana: 2
Total: 21.
Enchantments/Sorcery
1 mana: 3
2 mana: 10
3 mana: 2
4 mana: 4
5 mana: 0
6+ mana: 1
Total: 20
All lands: 19.
Please reply on your thoughts of these numbers.
Youre trying to over simplify something and shortsighting many factors the truly determine mana ratios and curves.
For those of us who are still learning how to play the game. Just numbers that are fairly easy to play with. You know, a plains/swamp deck with like 7 6+ mana cards is not very effective at all, etc.
There are many factors to add in Tosh. In a deck that doesn't ramp I'd say run 22-25 lands. From there it depends on what type of deck you want.
You can't really put a number on how many low mana cost creature you should run. For example: I could build a W/B deck that runs only creature CMC 6+, if I'm playing field control or reanimator that will be perfectly fine. But if I'm play those creatures without field control or {Rise From the Grave} effects then it'll never work.
There are many differents ways you can go with W/B. Give a deck type and we could help you with your build. As for putting a number on what you should use without a deck, well that's pointless.