Answer:
Step-by-step explanation:
Since the population standard deviation 
is unknown, and the sample standard deviation 
, must replace it, the 
distribution must be used for the confidence interval.
The sample size is n=8.
The degree of freedom is 
, 
.
With 95% confidence level, the 
(significance level) is 5%.
Hence with 7 degrees of freedom, 
. (Read from the t-distribution table see attachment)
The 95% confidence interval can be found by using the formula:
.
The sample mean is 
hours.
The sample sample standard deviation is 
hours.
We now substitute all these values into the formula to obtain:
.
We are 95% confident that the population mean is between 26.12 and 31.48 hours.
Answer:
13. -4 14. -11 15. 
Step-by-step explanation:
13. (1-3-10)/3
14. (-15+4-22)/3
15. (-7.5+3-6.5)/3
Answer:
parallel:
perpendicular:
Step-by-step explanation:
original line:
-7x + 8y = 4
m = 7/8
parallel:
m = 7/8
L: 7x - 8y = k
(4, -4) -> L
28 + 32 = 60 = k
L: 7x - 8y = 60
perpendicular:
m = -8/7
L: -8x + 7y = k
(4, -4) -> L
-32 + 28 = -4 = k
L: -8x -7y = -4
=> 8x + 7y = 4
Answer:
Step-by-step explanation:
