His mistake was in multiplying the 3 with the 12. He should have divided it from the 12 because that would have gotten rid of the 3 with the variable. It would also lead to the correct answer, which is b=4
Answer:
B. Mean absolute deviation
Step-by-step explanation:
The mean absolute deviation of a dataset is the average distance between each data point and the mean.
Answer:
1, 2, 3
Step-by-step explanation:
Answer:
4120
Step-by-step explanation:
Answer: 37
Step-by-step explanation:
Given : Significance level : 
Critical value : 
margin of error : E= 1 mile per gallon
Population standard deviation:
miles per gallon.
We know that when the population standard deviation is known then the formula to find the sample size is given by :

[Round to the next whole number.]
Hence, the required number of automobiles should be used in the test = 37