Under the “Landing Pages” tab in your Campaign Overview you will see another tab called “Variant Weighting”. 

This area will allow you to set how often you want a particular landing page variant to show in comparison to any others (e.g. 50/50, 75/25). 

Clicking ‘auto-adjust’ will automatically change the weighting of a variant so that the total equals 100%. 

Setting variant weighting is important when split-testing landing pages as you may want to keep your ‘champion’ variant showing more often.