Assuming the sample comes from a normal population, manufacturers tested 50 units and found the mean time between failures to be 2607 minutes, and the sample standard deviation to be 675. Find a 95% CI for the mean time between failures.
Assuming the sample comes from a normal population, manufacturers tested 50 units and found the mean...
A sample of 50 customers from a large normal population has a mean waiting time of 23 minutes. We know from past testing that the population standard deviation is 4 minutes. Determine a 95% confidence interval for the true mean(waiting time) of the population. Group of answer choices (34.5051, 65.4949) (21.8913, 24.1087) (23.4505, 26.5495) (44.5051, 75.4949)
After sampling 16 members of a normal population you find the sample mean equals 50 and the sample standard deviation, s, equals 10. Construct a 95% confidence interval estimate for mu, the population mean. A. 45.62 – 54.38 B. 44.67 – 55.33 C. 45.10 – 54.90 D. None of the above
A sample of 49 observations is taken from a normal population with a standard deviation of 10. The sample mean is 55. Determine the 99% confidence interval for the population mean. (Round your answers to 2 decimal places.) Confidence interval for the population mean is _______ and _______ .A research firm conducted a survey to determine the mean amount Americans spend on coffee during a week. They found the distribution of weekly spending followed the normal distribution with a population standard deviation...
1) A sample of size 25 is chosen from a population. Assume the probability distribution is normal. If the mean of the sample is 80 and the standard deviation is 6, find the lower bound of the 99% confidence interval. Round off to three decimal places. 2) A sample of size 36 is chosen from a population. The sample mean is 50 and the standard deviation is 5. Find the upper limit of the 95% confidence interval for the population...
A simple random sample of size 64 is drawn from a normal population with a known standard deviation σ. The 95% confidence interval for the population mean μ is found to be (12, 16). The approximate population standard deviation σ is:
A random sample of n - 16 scores is selecdted from a normal population with a mean of p - 50. After atreatment is administered to the individuals in the sample, the sample mean is found to be M -54 If the population standard deviation is σ-8, is the sample mean sufficient to conclude that the treatment has a significant effect? Use a two-tailed test with α-.05. (Hint: Recall that the critical value for a two-tailed test with α-.05 is...
The sample size needed to estimate a population mean to within 10 units was found to be 68. If the population standard deviation was 50, then the confidence level used was: Selected Answer: c. 0.9 Answers: a. 0.99 b. 0.95 c. 0.9 d. 0.85
If a sample of size n = 25 is chosen from a normal population, which one of the following is a 95% confidence interval for the population mean when the sample mean is 50 and the sample standard deviation is 6.5? O A 50 2.06(1.3) B 50 2.06(6.5) C 50 2.064(65) D 50 t 2.064(1.3)
In a random sample of 8 people, the mean commute time to work was 34.5 minutes and the standard deviation was 7.3 minutes. A 95% confidence interval using the t-distribution was calculated to be (28.4.40.6). After researching commute times to work, it was found that the population standard deviation is 9.4 minutes. Find the margin of error and construct a 95% confidence interval using the standard normal distribution with the appropriate calculations for a standard deviation that is known. Compare...
A survey of a random sample of 1000 smartphone owners found that the mean daily time spent communicating on a smart phone was 131.4 minutes if we assume the population standard deviation is 21.2 minutes the 95% confidence interval for the population mean will be 130.1<u<132. 7minutes. what is the meaning of these results