Business Data Analysis

BUSINESS DATA
ANALYSIS
STUDENT ID:
[Pick the date]

Question 1
In the given case, the sampling technique desired was probability based but essentially the
employee deployed convenience sampling which is a type of non-probability sampling
technique. One of the key features of a random sampling is that every element in the
population has equal chance of being selected which is vital to ensure that the sample is
representative of the population. However, in this case, the population was not considered.
Instead, the employee just went to a particular service station and collected requisite data
from first 50 motorists. This is quite likely to be biased as the demographics factors such as
gender, income, age would tend to drive the preference for car. However, since the sample
selection is driven by convenience of the researcher, hence it is quite likely that the 50 people
questioned do not represent the underlying population of town.
Question 2
The requisite tree diagram is shown below.
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Question 3
Sample size = 50
Mean = 53 hours
Standard deviation = 10 hours
95% confidence interval =?
Standard error = Standard deviation/ SQRT (Sample size) = 10/ SQRT (50) = 1.4142
The population standard deviation is unknown and thus, t value would be used in place of z
value.
Degree of freedom = 10-1 = 9
The t stat = 2.0096
Margin of error = t stat * Standard error = 2.0096*1.4142 = 2.8420
Lower limit of 95% confidence interval = Mean - Margin of error =53 -2.8420 = 50.16
Upper limit of 95% confidence interval = Mean + Margin of error =53 +2.8420 = 55.84
95% confidence interval = [50.16 55.84]
It can be said with 95% confidence that the mean time spent sleeping by all the students
during the last week would fall between 50.16 and 55.84 hours.
Question 4
(a)Scatter plot
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