Business Statistics: Hypothesis Testing

BUSINESS STATISTICS
ASSIGNMENT 2: HYPOTHESIS TESTING
STUDENT iD:
[Pick the date]

Question 1
Frequency table for arrival time
Histogram for arrival time
Less than
3 Over 3 to
6 Over 6 to
9 Over 9 to
12 Over 12
to 15 Over 15
to 18 Over 18
to 21 Over 21
to 24 Over 24
to 27 Over 27
to 30 Over 30
0
5
10
15
20
25
Histogram - Arrival Time Taken (Days)
Arrival Time (Days)
Frequency
The histogram highlights that the shape is almost symmetric thereby implying that the extent
of skew present in the data is almost zero.
Question 2
The descriptive statistics for the given data has been obtained using Excel.
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It is evident from the above descriptive statistics that mean time for a package to arrive in
Australia from a Hong Kong based seller is 14.26 days. The median value is 14.23 days
which is quite close to the mean since the extent of skew is almost zero. The extent of
dispersion in the time taken is moderate as indicated from the standard deviation, standard
variance and also range (Hillier, 2016).
Question 3
95% confidence interval for population mean has been computed as shown below.
Standard error = Standard deviation / Sqrt (Sample size) = 6.26/ sqrt (112) = 0.5915
The population standard deviation is known (6.26) and also the sample size is more than 30
and hence, it can be said as per Central Limit Theorem that z value would be used.
The z value for 95% confidence interval = 1.96
Margin of error = z value * Standard error = 1.96*0.5915 = 1.1594
Lower limit of 95% confidence interval = Mean - Margin of error = 14.26 – 1.1594 = 13.10
Upper limit of 95% confidence interval = Mean + Margin of error =14.26 + 1.1594 = 15.42
95% confidence interval for population mean = [13.10 15.42]
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