A researcher conducts a mileage economy test involving 80 cars. The frequency distribution describing average miles per gallon (mpg) appears in the following table. (a) What percentage of the cars got 35 mpg or more? (b) Is the distribution symmetric, positively skewed, or negatively skewed?
Inverse Normal Distribution
The method used for finding the corresponding z-critical value in a normal distribution using the known probability is said to be an inverse normal distribution. The inverse normal distribution is a continuous probability distribution with a family of two parameters.
Mean, Median, Mode
It is a descriptive summary of a data set. It can be defined by using some of the measures. The central tendencies do not provide information regarding individual data from the dataset. However, they give a summary of the data set. The central tendency or measure of central tendency is a central or typical value for a probability distribution.
Z-Scores
A z-score is a unit of measurement used in statistics to describe the position of a raw score in terms of its distance from the mean, measured with reference to standard deviation from the mean. Z-scores are useful in statistics because they allow comparison between two scores that belong to different normal distributions.
A researcher conducts a mileage economy test involving 80 cars. The frequency distribution describing average miles per gallon (mpg) appears in the following table.
(a) What percentage of the cars got 35 mpg or more?
(b) Is the distribution symmetric, positively skewed, or negatively skewed?
![Average MPG
15 < Aveg. MPG < 20
20 < Aveg. MPG < 25
25 < Aveg. MPG < 30
30 < Aveg. MPG < 35
35 < Aveg. MPG < 40
Aveg. MPG > 40
Frequency
15
25
20
10
6.
4](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F0a8e97e7-dbc6-464e-9104-96666bf376e5%2Fb4e6c9a6-fb4a-4286-aa02-e4f8799c1d2f%2Fe4pcw78_processed.png&w=3840&q=75)
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