Answer:
The population mean is 5 volts
Step-by-step explanation:
Output voltage is assumed to be normally distributed, with standard deviation 0.25 Volts
s=0.25
n = 8
Sample mean = 
Since n < 30 and population standard deviation is unknown
So, we will use t test
Formula : 
t=-1.69
Refer the t table for p value
Degree of freedom = n-1 = 8-1 = 7
So,
P value >α
So, We are failed to reject null hypothesis
Hence The population mean is 5 volts
The domain of the third piece of the graph is contained in interval <u>B. (12, 20)</u>.
<h3>What is the domain of a graph?</h3>
The domain of a graph consists of all the input values shown on the x-axis.
The input values (domain) are shown on the x-axis, unlike the range, whose output values are shown on the y-axis.
Therefore, the domain comprises the independent variables or values, which can be determined using the function, y = f(x).
Thus, the domain of the third piece of the graph can be determined in interval <u>B. (12, 20)</u>.
Learn more about domain and range at brainly.com/question/10197594 and brainly.com/question/2264373
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Girls: 81
boys: 75
4x +6 = 156
4x = 150
x = 37.5
2x = 75
girls: 75 + 6
boys: x
