Point Estimates & Confidence I

In our real world, where the quality and quantity of information ranges from excellent to terrible, would some measure of the certainty of the data tend to lead to better decisions?

Can point estimates and confidence intervals help to provide some measure as to the certainty of data values?

Point Estimates & Confidence I

A simple random sample of 8 employees is selected from a large firm. For the 8 employees, the number of days each was absent during the past month was found to be
1, 3, 3, 3, 1, 5, 4, and 3
(a) What is the point estimate for , the mean number of days absent for the firm’s employees? Round your answer to nearest hundredth.
=
(b) What is the point estimate for , the variance of the number of days absent? Round your answer to nearest hundredth.
=

Determine the limits of the 90% confidence interval for , given that
n = 86; = 60; and = 10.
95% CI = (n1,n2) where n1=lower limit and n2=upper limit

There are 300 students enrolled in Business Statistics. Historically, exam scores are normally distributed with a standard deviation of 21.25. Your instructor randomly selected a sample of 30 examinations and finds a mean of 67.2. Determine a 90% confidence interval for the mean score for all students taking the course.
90% CI = to

Point estimates & Confidence i

Please explain and show all calculations

1. If two large independent samples are taken from two populations, the sampling distribution of the difference between the two sample means can be determined how?

2. In my BMGT 230 class the fall semester is compared with my class 10 years ago. Please answer the following questions given: This Fall———–Tens Years Ago Mean 80————-85 Variance 100——–50 Sample 40———–60

a. the point estimate of the difference between means of the two populations is?

b. the point estimate of the standard deviation of the difference between the means of the two populations is ?

c. the 95% confidence interval for the difference between the two population means is?