Question

R Code Value P(T < t-stat) pt(t-value, df) P(T > t-stat) 1-pt (t-value, df) Please do 4 of the following 5 questions. Do more for the practice. If you do all of them, 1 EC on Quiz 12. Also, whenever you use R, please write out or print out your code via html document and label the question your R code is for! 1. A randomi sample of soil specimens was obtained and the amount of organic matter % in the soil was determined for each specimen, resulting in the accompanying data. soil c(1.14, 5.09, 97, 1.59, 4.6, .32, .55, 1.45, 0.14, 4.47, 1.2, 3.5, 5.02, 4.67, 5.22, 2.69, 3.98, 3.17, 3.03, 2.21, 0.69, 4.47, 3.31, 1.17, 76, 1.17, 1.57, 2.62, 1.66, 2.07) A statistician investigated this kind of soil data and decided it was approximately normally distributed. a. At a .1, carry out a 4-part hypothesis test to see if the true average percentage of organic matter in such soil is not 3%. b. Would your conclusion be different if a - .05 had been used?

Answer 1

a) H0: The true average percentage of organic matter in such soil is 3%

H1: The true average percentage of organic matter in such soil is not 3%

Let the los be alpha = 5%

R-code:

Test Statistic t = -1.753 and df = 29 ,

P-value = 0.09016

Here P-value > alpha 0.01 so we accept H0

b) Thus we conclude that the true average percentage of organic matter in such soil is 3%