Question

The mean life expectancy of a certain type of light bulb is 895 hours with a standard deviation of 18 hours. What is the approximate standard deviation of the sampling distribution of the mean for all samples with n = 40?
(Points : 3)
2.85 h

2.22 h

0.60 h

0.45 h

Answer 1

@undeadknight26

Answer 2

@jagr2713

Answer 3

Question 2.2. If 52% of the customers at a certain grocery store regularly use coupons, what is the approximate standard deviation of the sampling distribution of the proportion for samples of size 240?
(Points : 3)
2.1%

3.2%

4.7%

10.4%



Question 3.3. A researcher takes a simple random sample of 98 homes in a city and finds that the mean square footage is 1543 with a standard deviation of 177 square feet. What is the 90% confidence interval for the mean square footage of all the homes in that city?
(Points : 3)
(1508 ft2, 1578 ft2)

(1514 ft2, 1572 ft2)

(1525 ft2, 1561 ft2)

(1530 ft2, 1556 ft2)

Answer 4

Question 4.4. In a random sample of 54 downloadable books from a website, the mean cost is $7.34 with a standard deviation of $2.16. What is the 95% confidence interval for the mean cost of all the downloadable books on the website?
(Points : 3)
($6.58, $8.10)

($6.76, $7.92)

($7.05, $7.63)

($7.26, $7.42)



Question 5.5. In a random sample of 90 students in first grade, the mean hours of sleep per night was 9.2 with a standard deviation of 0.37. In a random sample of 70 students in 12th grade, the mean hours of sleep per night was 7.3 with a standard deviation of 0.58. Construct a 99% confidence interval for the difference between the mean hours of sleep.
(Points : 3)
(1.82 h, 1.98 h)

(1.79 h, 2.01 h)

(1.74 h, 2.06 h)

(1.69 h, 2.11 h)

Answer 5

@AnswerMyQuestions @DanJS @bruhhh