In a study conducted at (lie Virginia Polytechnic: Institute: and State University on the development of ectomycorrhizal. a symbiotic relationship between the roots of trees and a fungus in which minerals are transferred from the fungus to the trees and sugars from the trees to the fungus, 20 northern red oak seedlings with the fungus Pisolithus tinctures were grown in a greenhouse. All seedlings were planted in the same type of soil and received the same amount of sunshine and water. Half received no nitrogen at planting time: to serve as a control and the other half received 368 ppm of nitrogen in the form NaNO₃. The stem weights, recorded in grams, at the end of 140 days were recorded as follows: Construct a 95% confidence interval for the difference in the mean stem weights between seedlings that receive no nitrogen and those: that receive 308 ppm of nitrogen. Assume the populations to be normally distributed with equal variances.

Transcribed Image Text:

No Nitrogen 0.32 Nitrogen 0.26 0.43 0.47 0.49 0.52 0.75 0.53 0.28 0.37 0.47 0.43 0.30 0.42 0.38 0.43 0.79 0.86 0.62 0.46