MATH 1280 wa2
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School
McGill University *
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Course
1280
Subject
Mathematics
Date
Jan 9, 2024
Type
docx
Pages
4
Uploaded by antifan
MATH 1280-01
Written Assignment Unit 2
Hitesh Verma (Instructor)
Forty randomly selected students were asked the number of pairs of sneakers they owned.
Let X = the number of pairs of sneakers owned. The results are as follows:
Pairs of sneakers owned
X Frequency
1
2
2
5
3
8
4
12
5
12
6
0
7
1
1.
Find the mean
2.
Find the samples standard deviation,
s
.
3.
Complete the Relative Frequency column and the Cumulative Relative Frequency
Column.
4.
Find the first quartile.
5.
Find the median.
6.
Find the third quartile.
7.
What percent of the students owned at least five pairs?
8.
Find the 40th percentile.
9.
Find the 90th percentile.
Mean
The mean, denoted by μ, represents the average value of all observations in the dataset. To
calculate the mean, we sum up all the values of X and divide by the total number of observations:
Mean (μ) = (ΣX)/n = (122 + 53 + 8 + 4 + 1 + 2 + 5 + 1 + 2 + 6 + 0 + 7 + 1)/40 = 3.78
Sample Standard Deviation
The sample standard deviation, denoted by s, measures the variability or dispersion of the data
around the mean. To calculate the sample standard deviation, we first calculate the squared
deviations from the mean for each observation:
(X - μ)^2 = (122 - 3.78)^2 + (53 - 3.78)^2 + ... + (7 - 3.78)^2
Then, we sum up these squared deviations and divide by n - 1:
Variance (σ^2) = Σ(X - μ)^2 / (n - 1)
Sample Standard Deviation (s) = √(Variance)
Sample Standard Deviation (s) = √(10,624.72 / 39) = 1.29
Relative Frequency and Cumulative Relative Frequency
Relative frequency is the proportion of observations that fall within a given category. Cumulative
relative frequency is the proportion of observations that fall within a given category or any
preceding categories.
Pairs of sneakers
owned
Frequency
Relative
Frequency
Cumulative Relative
Frequency
1
2
0.050
0.050
2
5
0.125
0.175
3
8
0.200
0.375
4
12
0.300
0.675
5
12
0.300
0.975
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