# statistics

posted by .

A 90% confidence interval for a population mean based on 144 observations is computed to be (2.7,3.4). How many observations must be made so that 90% confidence interval will specify the mean to within ± 0.2

• statistics -

n=140

## Similar Questions

1. ### statistics

What do confidence intervals represent? What is the most controllable method of increasing the precision of or narrowing the confidence interval?
2. ### statistics

Consider a 95% confidence interval for a population mean constructed from a random sample of 250 observations taken from a Normal population. Sigma is known to be 14. If we were to construct another 95% confidence interval, this time …
3. ### statistics

Consider a 95% confidence interval for a population mean constructed from a random sample of 250 observations taken from a Normal population. Sigma is known to be 14. If we were to construct another 95% confidence interval, this time …
4. ### Statistics

Which of the following statements best describes the uncertainty associated with a 95% confidence interval for a population proportion, computed from a simple random sample?
5. ### Statistics

A 95% confidence interval for a population mean, ?
6. ### Statistics

Suppose x has a mound-shaped distribution with sigma = 9 . A random sample of size 36 has sample mean 20. Is it appropriate to use a normal distribution to compute a confidence interval for the population mean m?
7. ### Statistics

Multiple Choice Which of the following statements is true about the 95% confidence interval of the average of a sample?
8. ### Statistics

The standard deviation for a population is σ = 15.3. A sample of 36 observations selected from this population gave a mean equal to 74.8. a) Make a 90% confidence interval for μ b) Construct a 95% confidence interval for …
9. ### Statistics

A random sample of 90 observations produced a mean that = 25.9 and a standard deviation s =2.4 (a)Find a 95% confidence interval for u (b)Find a 90% confidence interval for u (c)Find a 99% confidence interval for u (Use integers or …
10. ### Statistics

A confidence interval for a population mean has a margin of error of 3.1. a)Determine the length of the confidence interval. b)If the sample mean is 56.7, obtain the confidence interval.

More Similar Questions

Post a New Question