Date Day Time Region Card Type Gender Buy Category Items Ordered Total Cost High Item 6-Mar Sun Morning West AJ Female High 4 $136.97 $79.97 6-Mar Sun Morning West Other Female Medium 1 $25.55 $25.55 6-Mar Sun Afternoon West AJ Female Medium 5 $113.95 $90.47 6-Mar Sun Afternoon NorthEast Other Female Low 1 $6.82 $6.82 6-Mar Sun Afternoon West AJ Male Medium 4 $147.32 $83.21 6-Mar Sun Afternoon NorthEast Other Female Medium 5 $142.15 $50.90 7-Mar Mon Evening West Other Male Low 1 $18.65 $18.65 7-Mar Mon Evening South Other Male High 4 $178.34 $161.93 7-Mar Mon Evening West Other Male Low 2 $25.83 $15.91 8-Mar Tue Morning MidWest Other Female Low 1 $18.13 $18.13 8-Mar Tue Morning NorthEast AJ Female Medium 2 $54.52 $54.38 8-Mar Tue Afternoon South Other Male Medium 2 $61.93 $56.32 9-Mar Wed Morning NorthEast AJ Male High 3 $147.68 $96.64 9-Mar Wed Afternoon NorthEast Other Male Low 1 $27.24 $27.24 10-Mar Thu Morning West Other Female Low 3 $46.18 $44.27 10-Mar Thu Afternoon West Other Male Low 5 $107.44 $91.64 10-Mar Thu Afternoon South AJ Female Medium 6 $96.53 $93.68 10-Mar Thu Afternoon West AJ Female Medium 4 $77.44 $77.28 11-Mar Fri Morning South Other Male Low 1 $15.19 $15.19 11-Mar Fri Afternoon South Other Male Medium 1 $45.52 $45.52 12-Mar Sat Morning West Other Male High 4 $157.05 $146.28 12-Mar Sat Afternoon West Other Male Medium 2 $51.95 $30.40 12-Mar Sat Evening West AJ Female High 9 $429.98 $381.33 13-Mar Sun Afternoon South Other Female Low 1 $33.37 $33.37 13-Mar Sun Evening West Other Male Medium 3 $71.84 $34.13 14-Mar Mon Morning NorthEast AJ Female Medium 5 $139.51 $133.11 14-Mar Mon Afternoon South Other Male Medium 3 $78.46 $58.53 14-Mar Mon Evening MidWest Other Male High 3 $125.13 $103.31 15-Mar Tue Afternoon MidWest Other Male Medium 1 $14.76 $14.76 15-Mar Tue Afternoon South AJ Female High 2 $83.38 $71.02 16-Mar Wed Morning West Other Female High 3 $104.91 $47.79 This dataset shows a sample of customers’ orders from AJ Madison, an online retailer of electronic appliances. a)Calculate a 95% confidence interval for the proportion of all customers whose total cost is more than $100. b)Calculate a 99% confidence interval for the mean total cost for NorthEast Transactions. c)Calculate a 95% confidence interval for the standard deviation of total cost for all customers (assuming that total cost follows normal distribution).
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.
Date | Day | Time | Region | Card Type | Gender | Buy Category | Items Ordered | Total Cost | High Item |
6-Mar | Sun | Morning | West | AJ | Female | High | 4 | $136.97 | $79.97 |
6-Mar | Sun | Morning | West | Other | Female | Medium | 1 | $25.55 | $25.55 |
6-Mar | Sun | Afternoon | West | AJ | Female | Medium | 5 | $113.95 | $90.47 |
6-Mar | Sun | Afternoon | NorthEast | Other | Female | Low | 1 | $6.82 | $6.82 |
6-Mar | Sun | Afternoon | West | AJ | Male | Medium | 4 | $147.32 | $83.21 |
6-Mar | Sun | Afternoon | NorthEast | Other | Female | Medium | 5 | $142.15 | $50.90 |
7-Mar | Mon | Evening | West | Other | Male | Low | 1 | $18.65 | $18.65 |
7-Mar | Mon | Evening | South | Other | Male | High | 4 | $178.34 | $161.93 |
7-Mar | Mon | Evening | West | Other | Male | Low | 2 | $25.83 | $15.91 |
8-Mar | Tue | Morning | MidWest | Other | Female | Low | 1 | $18.13 | $18.13 |
8-Mar | Tue | Morning | NorthEast | AJ | Female | Medium | 2 | $54.52 | $54.38 |
8-Mar | Tue | Afternoon | South | Other | Male | Medium | 2 | $61.93 | $56.32 |
9-Mar | Wed | Morning | NorthEast | AJ | Male | High | 3 | $147.68 | $96.64 |
9-Mar | Wed | Afternoon | NorthEast | Other | Male | Low | 1 | $27.24 | $27.24 |
10-Mar | Thu | Morning | West | Other | Female | Low | 3 | $46.18 | $44.27 |
10-Mar | Thu | Afternoon | West | Other | Male | Low | 5 | $107.44 | $91.64 |
10-Mar | Thu | Afternoon | South | AJ | Female | Medium | 6 | $96.53 | $93.68 |
10-Mar | Thu | Afternoon | West | AJ | Female | Medium | 4 | $77.44 | $77.28 |
11-Mar | Fri | Morning | South | Other | Male | Low | 1 | $15.19 | $15.19 |
11-Mar | Fri | Afternoon | South | Other | Male | Medium | 1 | $45.52 | $45.52 |
12-Mar | Sat | Morning | West | Other | Male | High | 4 | $157.05 | $146.28 |
12-Mar | Sat | Afternoon | West | Other | Male | Medium | 2 | $51.95 | $30.40 |
12-Mar | Sat | Evening | West | AJ | Female | High | 9 | $429.98 | $381.33 |
13-Mar | Sun | Afternoon | South | Other | Female | Low | 1 | $33.37 | $33.37 |
13-Mar | Sun | Evening | West | Other | Male | Medium | 3 | $71.84 | $34.13 |
14-Mar | Mon | Morning | NorthEast | AJ | Female | Medium | 5 | $139.51 | $133.11 |
14-Mar | Mon | Afternoon | South | Other | Male | Medium | 3 | $78.46 | $58.53 |
14-Mar | Mon | Evening | MidWest | Other | Male | High | 3 | $125.13 | $103.31 |
15-Mar | Tue | Afternoon | MidWest | Other | Male | Medium | 1 | $14.76 | $14.76 |
15-Mar | Tue | Afternoon | South | AJ | Female | High | 2 | $83.38 | $71.02 |
16-Mar | Wed | Morning | West | Other | Female | High | 3 | $104.91 | $47.79 |
This dataset shows a sample of customers’ orders from AJ Madison, an online retailer of electronic appliances.
a)Calculate a 95% confidence interval for the proportion of all customers whose total cost is more than $100.
b)Calculate a 99% confidence interval for the
c)Calculate a 95% confidence interval for the standard deviation of total cost for all customers (assuming that total cost follows
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