I disagree. While there are some searchers who are curious about the subtleties of the differences between the speed of sound through various mediums and at different altitude levels, most people searching for that basic question are satisfied to know that the speed of sound through air is about 750mph, which is why I said that it would satisfy about 99% of searchers. People who are interested in digging in further can comb through the rest of the results, or further specify that they want to know the speed of sound through water or at 35,000 feet above sea level. Just as some people who search for "What is the height of the Empire State Building?" may want to know what is the height of the highest occupied floor, or just the structure without the mast, most want to know how many feet is the distance from the base to the top?
By trying to satisfy every searcher for these types of queries, you will be making searching more cumbersome for the vast majority of people, which is why I think that providing a single, easy to view answer that is likely to satisfy the person who entered the search a calculated risk that's worth taking.
It's for the answers that wouldn't satisfy most searchers that I don't think a definitive answer should be provided, as it is likely to be either wrong, or just one of many possible answers that the searcher is looking for.
It reminds me of a picture I once saw of MS Word when every single banner is enabled. The menus occupy half the screen. Even though there is some power user somewhere who really needs that menu option, the reality is that virtually nobody else does. So while that user has to go through the pain to figure out how to enable that banner, his pain makes the product easier to use for 99.99999% of users.