Soil pH is an important variable in the design of structures that will contact the soil. Nine test samples of soil from a potent
ial construction site gave readings of 7.3 6.5 6.4 6.1 6.0 6.5 6.2 5.8 6.7
Assuming that soil pH is normally distributed, find the 90% lower confidence bound for the true average soil pH at the site.