Assume that the mean length of all cell phone conversations in a certain country is 3.75 minutes and the standard deviation is 4.3 minutes. Complete parts (a) through (c) below. a. Describe the shape of the distribution of the length of cell phone conversations in this population. Do you expect it to be approximately Normally distributed, right-skewed, or left-skewed? Explain your reasoning. The distribution will be ? because the values will be? b. Suppose that, using a phone company's records, we randomly sample 100 phone calls. We calculate the mean length from this sample and record the value. We repeat this thousands of times. What will be the (approximate) mean value of the distribution of these thousands of sample means? nothing minutes (Type an integer or a decimal. Do not round.) c. Refer to part (b). What will be the standard deviation of this distribution of thousands of sample means? nothing minutes (Type an integer or a decimal. Do not round.)
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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