Answer:
The 90% confidence interval for the mean usage of electricity is between 17.4 kwH and 17.6 kwH
Step-by-step explanation:
We have that to find our 
level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of 
So it is z with a pvalue of 1-0.05 = 0.95, so z = 1.645
Now, find the margin of error M as such
In which 
is the standard deviation of the population and n is the size of the sample.
So
The lower end of the interval is the mean subtracted by M. So 17.5 - 0.14 = 17.4 kwH
The upper end of the interval is M added to the mean. So 17.5 + 0.14 = 17.6 kwH
The 90% confidence interval for the mean usage of electricity is between 17.4 kwH and 17.6 kwH
Answer:32
Step-by-step explanation:
Answer:
The output is 23
Step-by-step explanation:
we know that
f(x) ----> is the output
x ----> is the input
we have that
f(x)=3x-1
For x=8 (input)
Find the value of f(x) (output)
f(8)=3(8)-1=23
The output is 23
Answer:
b
Step-by-step explanation:
Distribute parenthesis and collect like terms, noting that the second parenthesis is distributed by - 1
(4x² - 8xy +2y²) - (9x² - 4xy - 7y²)
= 4x² - 8xy + 2y² - 9x² + 4xy + 7y² ← collect like terms
= (4x² - 9x²) + (- 8xy + 4xy) + (2y² + 7y²)
= - 5x² - 4xy + 9y² → b
