A construction company with two black hose has contracted to dig a long trench for drainage pipes the larger black who can dig the entire trench by it self in 12 days the smaller Bracco can dig the entire trench by his self in 14 days the large black oh begins working on the trench by the south but after seven days it is transferred to a different job and a smaller black hole begins working on the trench how long will take the smaller bike how to complete the job

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.