You are working as a forester and are told the average diameter at breast height (dbh) of a 100 year old sequoia tree is 18.9 inches. You decide to test whether this is an accurate number. You collect dbh of 25 trees in the forest you are working in. Explain what your null hypothesis and alternative hypothesis are (you must explain and write in mathematical notation ). Is your hypothesis directional or non-directional? Explain why.