statistics

A simple random sample of 60 items resulted in a sample mean of 80. The population standard deviation is 15.
a) Compute the 95 % confidence interval for the population mean.
b) Assume that the same sample mean was obtained from a sample of 120 items. Provide a 95% confidence interval for the population mean.
c)What is the effect of a larger sample size on the margin of error?

  1. 👍 0
  2. 👎 0
  3. 👁 1,222
  1. a) 95% = mean ± 1.96 SD

    b) 95% = mean ± 1.96 SEm

    SEm = SD/√(n-1)

    c) margin of error decreases.

    1. 👍 0
    2. 👎 2
  2. xz

    1. 👍 0
    2. 👎 0
  3. I would really like to know this answer, i am not good at doing the calculations....can someone help please?

    1. 👍 0
    2. 👎 0
  4. How do you get 1.96

    1. 👍 0
    2. 👎 0

Respond to this Question

First Name

Your Response

Similar Questions

  1. statistics

    A simple random sample of 40 items resulted in a sample mean of 25. The population standard deviation is 5. a. What is the standard error of the mean (to 2 decimals)? b. At 95% confidence, what is the margin of error (to 2

  2. Math I need help ASAP!

    1. which of the following is true of a random sample? a. it is the only way to sample a population. b. each member of the sample is a volunteer. c. it is always the easiest way to sample a population. d. each member of the

  3. statistics

    A simple random sample of 50 items from a population with σ  6 resulted in a sample mean of 32. a. Provide a 90% confidence interval for the population mean

  4. Statistics

    A 95% confidence interval for a population mean, ?, is given as (18.985, 21.015). This confidence interval is based on a simple random sample of 36 observations. Calculate the sample mean, x ?, and the sample standard deviation,

  1. stats

    Three firms carry inventories that differ in size. Firm A's inventory contains 2000 items, firm B's inventory contains 5000 items, and firm C's inventory contains 10,000 items. The population standard deviation for the cost of the

  2. Statistics (42)

    A simple random sample of 60 items resulted in a sample mean of 96. The population standard deviation is 16. a. Compute the 95% confidence interval for the population mean (to 1 decimal). ( , ) b. Assume that the same sample mean

  3. Math

    1.)Suppose you interview 10 randomly selected workers and ask how many miles they commute to work. You'll compute the sample mean commute distance. Now imagine repeating the survey many, many times, each time recording a different

  4. business statistics

    A random sample of size 15 taken from a normally distributed population reveled a sample mean of 75 and a sample variance of 25. The upper limit of a 95% confidence interval for the population mean would equal?

  1. Government

    1) The portion of the population selected to participate in a poll is known as the a. public b. population c. deliberative group d. sample e. focus group 2) A sample that does not overrepresent any portion of the population and

  2. Statistics

    A new manager, hired at a large warehouse, was told to reduce the 26% employee sick leave. The manager introduced a new incentive program for the company's employees with perfect attendance. The manager decides to test the new

  3. Economics (41)

    A simple random sample of 60 items resulted in a sample mean of 96. The population standard deviation is 16. a. Compute the 95% confidence interval for the population mean (to 1 decimal). ( , ) b. Assume that the same sample mean

  4. stats

    A simple random sample of 30 items resulted in a sample mean of 15. The population standard deviation is σ = 8. Round your answers to two decimal places. a. What is the standard error of the mean, σx? b. At 95% confidence, what

You can view more similar questions or ask a new question.