A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

The Water Department checks the city water supply on a regular basis for contaminants such as trihalomethanes (THMs). The Water Department takes 200 samples and estimates that the concentration of THMs in your drinking water is 3 ppb (parts per billion), with a standard deviation of 0.3 ppb. Assuming the samples were random and unbiased, how much confidence can you have in this data?

  • This Question is Closed
  1. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    A. 99.7% confident the average concentration of PCBs in the water supply is between 2.7 ppb and 3.3 ppb. B. 97% confident the average concentration of PCBs in the water supply is between 2.6 ppb and 3.8 ppb. C. 68% confident the average concentration of PCBs in the water supply is between 2.9 ppb and 3.1 ppb. D. 95% confident the average concentration of PCBs in the water supply is between 2.4 ppb and 3.6 ppb.

  2. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.