statistics

2. The new Twinkle bulb has a standard deviation hours. A random sample of 77 light bulbs is selected from inventory. The sample mean was found to be 492 hours.
a. Find the margin of error E for a 90% confidence interval.
Round your answer to the nearest hundredths.

  1. 👍 0
  2. 👎 0
  3. 👁 71
  1. Margin of error = z-value (sd/√n)

    Find the z-value corresponding to 90% confidence using a z-table.

    sd = standard deviation
    n = sample size

    I hope this will help get you started.

    1. 👍 0
    2. 👎 0
    posted by MathGuru
  2. Please someone help me? The new twinkle bulb has a standard deviation 35 hours. A random sample of 50 light bulbs is selected from inventory. The sample mean was found to be x=500 hrs. Find the margin of error for 95%, construct a 95% confidence interval for the mean life of all Twinkle bulbs. I am desperate.

    1. 👍 0
    2. 👎 0

Respond to this Question

First Name

Your Response

Similar Questions

  1. statitics

    a light bulb manufacture gaurentees that the mean life of a certain type of bulb is at least 875 hours. A random sample of 40 light bulbs has a mean life of 863 hours with a standard deviation of 50. a=0.04

    asked by jamie on April 18, 2011
  2. statistics

    1. The new Twinkle bulb has a standard deviation σ = 34 hours. A random sample of 77 light bulbs is selected from inventory. The sample mean was found to be x= 492 hours. Question: Find the margin of error E for a 90% confidence

    asked by looking for someone to varify my work please on April 6, 2010
  3. math

    1) A light bulb producing company states that its lights will last an average of 1200 hours with a standard deviation of 200 hours. A sample of 100 light bulbs from the company were tested and the researcher found that the average

    asked by Alexus on July 16, 2012
  4. maths

    the life span of an electric bulb is normally distribution with mean 5500 light hours and standard deviation of 1200 light hours . what is the probability that a randomly selected bulb which lasts more than 6000 light hours?

    asked by ragul on December 31, 2015
  5. Business Statistics

    The quality control manager at a light bulb factory needs to estimate the mean life of a large shipment of light bulbs. The manufacturer's specifications are that the standard deviations is 100 hours. A random sample of 64 light

    asked by Tim on September 20, 2015
  6. Math

    Suppose the number of hours a type of light bulb will burn is normally distributed with a mean 84 with a standard deviation of 9 hours. what is the probability one of these bulbs will burn for more than 90 hours? If a sample of 24

    asked by Jess on April 16, 2019
  7. Statistics

    A company has developed a new type of light bulb, and wants to estimate its mean lifetime. A simple random sample of 12 bulbs had a sample mean lifetime of 692 hours with a sample standard deviation of 30 hours. It is reasonable

    asked by Sara on July 1, 2013
  8. Statistics

    Can anyone tell me how to use TI-84 calculator to solve this problem??? A company has developed a new type of light bulb, and wants to estimate its mean lifetime. A simple random sample of 12 bulbs had a sample mean lifetime of

    asked by Anonymous on June 29, 2013
  9. Statistics

    The mean life expectancy of a certain type of light bulb is 945 hours with a standard deviation of 21 hours. What is the approximate standard deviation of the sampling distribution of the mean for all samples with n=50?

    asked by tf9346 on May 9, 2016
  10. Math

    A consumer buys n light bulbs, each of which has a lifetime that has a mean of 800 hours, a standard deviation of 100 hours, and a normal distribution. A light bulb is replaced by another as soon as it burns out. Assuming

    asked by Alex on April 27, 2011

More Similar Questions