Let x represent the dollar amount spent on supermarket impulse buying in a 10-minute (unplanned) shopping interval. Based on a newspaper article, the mean of the x distribution is about $10 and the estimated standard deviation is about $6. A USE SALT (a) Consider a random sample of n = 40 customers, each of whom has 10 minutes of unplanned shopping time in a supermarket. From the central limit theorem, what can you say about the probability distribution of x, the average amount spent by these customers due to impulse buying? What are the mean and standard deviation of the x distribution? O The sampling distribution of x not normal. O The sampling distribution of x is approximately normal with mean u- = 10 and standard error o, = $6. O The sampling distribution of x is approximately normal with mean u, = 10 and standard error o; = $0.15. O The sampling distribution of x is approximately normal with mean u, = 10 and standard error o, = $0.95. Is it necessary to make any assumption about the x distribution? Explain your answer. O It is not necessary to make any assumption about the x distribution because u is large. O It is necessary to assume that x has a large distribution. O It is not necessary to make any assumption about the x distribution because n is large. O It is necessary to assume that x has an approximately normal distribution. (b) What is the probability that x is between $8 and $12? (Round your answer to four decimal places.) (c) Let us assume that x has a distribution that is approximately normal. What is the probability that x is between $8 and $12? (Round your answer to four decimal places.)
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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