Roughuiyatou's clothing store recorded the amounts paid by the sample of 200 customers who made purchases at the store last Saturday. The following histogram summarizes the data. Purchase amounts at Roughuiyatou's clothing store n= 200 0.35 0.3 0.25 0.2 E 0.15 R 0.1 0.05 20 30 40 50 60 70 80 90 Dollars 4.а. What is the unit of observation in this sample? 4.b. What is the variable collected? 4.c. Which measurement class contains the highest proportion of observations? 4.d. Calculate the approximate proportion of customers who made a purchase of less than $20. 4.e. Calculate the approximate proportion of customers who made a purchase of greater than S60. 4.f. Calculate the number of customers who made a purchase of between $20 and $30.
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.
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