We are given the following data:
Sample Size = n = 1000
Sample Mean = u = 15 hours
Population Standard Deviation = s = 2 hours
Since we know the population standard deviation, we can use z distribution to find the confidence interval about the mean. z value for 95% confidence interval is 1.96.
Formula for the confidence interval is:

Using the values in the formula, we get:

Therefore, the 95% confidence interval about the population mean is 14.88 hours to 15.12 hours. So B option is the correct answer.
Answer:
should be -29.29 %
Step-by-step explanation:
The correct answer is x=-2
Answer:
2.5
Step-by-step explanation:
2.5 is the only positive number amongst the options, so it must be the greatest.
Answer:
x = 7, y = 30 and x = 3, y = 10
Step-by-step explanation:
5x - y = 5, then y = 5x - 5
2y - x^2 = 11
2(5x - 5) - x^2 = 11
10x - 10 - x^2 = 11
-x^2 + 10x -10 = 11
-x^2 + 10x -21 = 0
x^2 - 10x + 21 = 0
(x - 7)(x - 3) = 0
x = 7, y = 30
x = 3, y = 10