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Question 1
Measures of central tendency refers to values such as mean, median, and mode that present
a typical score about the middle of data distribution
Measures of variation refers to values such as range and standard deviation that shows
spread of data among scores within a distribution
Question 2
Random sampling samples are selected by using chance methods or random numbers
Systematic sampling objects are numbered in ascending order and every kth value is
selected.
Stratified sampling- samples are selected by Divide the population into groups
Cluster sampling- are selected by Divide the population into sections
Convenience Sampling- sampling only people who are easy to reach
Question 3
Sampling is done where the population of interest is large and data collection would
consume time and resources. Sample represent actual population. Depending on the
nature of study and the study goals, sampling methods vary. The most common sampling
method is simple random sampling
Question 4
Inappropriate sampling could lead to biasness hence wrong interpretation. Reliability and
validity of collected data and sampling methods are key to good statistical study. Some
people may use statistics to depict their own thoughts for personal gains or malicious acts.
For instance, election polls could be manipulated to give a false impression of the real voter
support on ground.
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Question 5
A discrete random variable has a countable number of possible values. A continuous
random variable has an infinite number of possible values, all the values in an interval.
Question 6
a)
The probability of success stays the same for each trial.
The random variable counts the number of successes in a fixed number of trials.
b)
p=1/4=0.25
n=10
x=3
P(x) = 󰇡
󰇢
󰇛 󰇜

P(x=3) =󰇡

󰇢
󰇛 󰇜

= 0.25028
c)
P(x<3) = p(x=0) +p(x=1) +p(x=2)
=󰇡

󰇢
󰇛 󰇜

+󰇡

󰇢
󰇛 󰇜

+󰇡

󰇢
󰇛 󰇜

=0.0563+0.1877+0.2816
=0.5256
d)
P(x>8) = p(x=9) +p(x=10)
=󰇡

󰇢
󰇛 󰇜

+󰇡


󰇢

󰇛 󰇜

= 2.86*

+9.54*

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=2.96 

Question 7
Z=

Question 8
P (z<0) =0.5
P (z<2) = 0.9772
P (0<z<2) =) = 0.9772-0.5 = 0.4772
Question 9
a)
mean
104
standard
deviation
6
b)
68-95-99.7 (empirical rule)
Z=

= -2
Z=

= 2
The probability within 2 standard deviation is 95%
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