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Answer:
Step-by-step explanation:
Let:
We need to eliminate one of the variables, so let's use elimination method. First multiply (1) by 2
Now subtract (2) from 2*(1) in order to eliminate x:
Solving for y:
Multiplying both sides by -1
Finally, replacing the value of y in (1)
Solving for x:
add 41 to both sides:
Multiply both sides by 1/2:
Answer:
And the best option for this case would be:
a. (17.5, 21.7)
Step-by-step explanation:
Information given
represent the sample mean
population mean
represent the population deviation
n=42 represent the sample size
Confidence interval
The confidence interval for the mean is given by the following formula:
(1)
The degrees of freedom, given by:
Since the Confidence is 0.98 or 98%, the significance would be and
, and the critical value would be
Replacing we got:
And the best option for this case would be:
a. (17.5, 21.7)