Two groups of 10 soybean plants are measured for height in meters. group a receives an experimental fertilizer while group b receives the normal fertilizer treatment. group a: 1.4, 1.3, 1.5, 1.5, 1.7, 1.3, 1.4, 1.3, 1.5, 1.4 group b 1.2, 1.3, 1.0, 1.2, 1.3, 1.4, 1.4, 1.2, 1.3, 1.3 find the mean of group a and b and the mean difference. group a mean: group b mean: difference of means: the groups are re- randomized and the mean differences are represented in the dot plot. is the mean difference between the experimental and normal fertilizer significant?

Arandom sample of 15 observations is used to estimate the population mean. the sample mean and the standard deviation are calculated as 172 and 63, respectively. assume that the population is normally distributed. a. with 99 confidence, what is the margin of error for the estimation of the population mean? b. construct the 99% confidence interval for the population mean. c. construct the 95% confidence interval for the population mean. d. construct the 83% confidence interval for the population mean. hint: you need to use excel function =t.inv.2t to find the value of t for the interval calculation.