1. Assuming x is normally distributed, use the following information to compute a 90% confidence interval to estimate.
| 313 |
320 |
319 |
340 |
325 |
310 |
| 321 |
329 |
317 |
311 |
307 |
318 |
(Round the answers to 2 decimal places.)
≤μ≤
2. A community health association is interested in estimating the average number of maternity days women stay in the local hospital. A random sample is taken of 36 women who had babies in the hospital during the past year. The following numbers of maternity days each woman was in the hospital are rounded to the nearest day.
1
|
3 |
4 |
3 |
2 |
5 |
3 |
1 |
4 |
3 |
4
|
2 |
3 |
5 |
3 |
2 |
4 |
3 |
2 |
2 |
1
|
6 |
3 |
4 |
3 |
3 |
5 |
2 |
3 |
2 |
| 3 |
5 |
4 |
3 |
5 |
3 |
|
Use these data and a population standard deviation of 1.13 to construct a 98% confidence interval to estimate the average maternity stay in the hospital for all women who have babies in this hospital.
(Round the intermediate values to 3 decimal places. Round your answers to 3 decimal places.)
≤μ ≤
3. Suppose a random sample of size 64 is drawn from a population with a mean of 277. If 86% of the time the sample mean is less than 280, what is the population standard deviation?
(Round your answer to 2 decimal places.)
4. Suppose a subdivision on the southwest side of Denver, Colorado, contains 1,700 houses. The subdivision was built in 1983. A sample of 110 houses is selected randomly and evaluated by an appraiser. If the mean appraised value of a house in this subdivision for all houses is $229,000, with a standard deviation of $8,500, what is the probability that the sample average is greater than $230,500?
(Round the values of z to 2 decimal places. Round your answer to 4 decimal places.)