<prompt> Human: I was reading through this guide:And am struggling to follow the section about approximating the US Stocks:The lowest cost US mutual fund choices, ideally averaging out to Morningstar large size category and the Morningstar blend style category...If you end up on the last option and your plan only has growth and value funds, you can approximate a blend style fund by combining equal proportions of growth and value. Because large-cap stocks constitute about 80 of the US stock market, you also want to try to only use small-cap and mid-cap funds for about 20 of your US stock allocation.Does that mean just find the best Large Cap Blend style for 80, and mid and small cap blend for the remainder?Is that 20 split 5050?Should the Mid Cap and Small Cap be Blend style as well?What about the Value Or Growth Styles for Large Cap, Mid Cap, and Small Cap? Ignore them?Basically, Im having trouble figuring out one would use various caps and styles to approximate the US Stock Market.  <response>: If you post a list of the funds available to you and their expense ratios someone could probably help you better. 