How to calculate whether you have enough mana, continued

What are the chances that you will have one land to play for each of the first four turns? Using Deck-u-lator to answer that question was the topic of an earlier article.  Here is a graph showing the chance of having one land on turn one, two land on turn two, and so on for different 60 card decks.

With 20 land, there is a 54% chance to have 4 land on turn 4
With 24 land, there is a 57% chance to have 5 land on turn 5
With 28 land, there is a 51% chance to have 7 land on turn 7