Exam questions on descriptive statistics (easy)

Task 1

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# Task 1: Arithmetic Mean of a Small Group of Scores
# We have 5 scores, calculate the mean, and interpret it.
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# 1. Create the dataset
scores <- c(12, 15, 14, 10, 13) # Create vector 'scores' with five values

# 2. Display the dataset
scores # Display all five scores in the vector
#> [1] 12 15 14 10 13

# 3. Calculate the arithmetic mean
mean(scores) # Calculate the mean of the five scores
#> [1] 12.8

# Interpretation questions:
# - What does the mean (12.8 here) say about the average performance of this group?
# - Would your assessment change if one value were very large or very small?

Task 2

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# Task 2: Median of Waiting Times
# We have 5 waiting times, determine the median, and discuss its robustness.
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# 1. Create the dataset
waits <- c(5, 7, 3, 10, 6) # Vector 'waits' contains five waiting times in minutes.

# 2. Display the dataset
waits # Display all waiting times
#> [1] 5 7 3 10 6

# 3. Calculate the median
median(waits) # Output the median of the waiting times
#> [1] 6

# Interpretation questions:
# - Why is the median (6 here) more robust against outliers than the arithmetic mean?
# - How would the median change if one waiting time were 100?

Task 3

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# Task 3: Temperature range
# We have 5 temperature measurements, calculate the range, and interpret it.
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# 1. Create the dataset
temps <- c(20, 22, 19, 25, 23) # Five temperature values in °C

# 2. Determine the minimum and maximum
range(temps) # Display the smallest and largest temperature value
#> [1] 19 25

# 3. Calculate the range
diff(range(temps)) # Difference between the maximum and minimum → range
#> [1] 6

# Interpretation questions:
# - What does a range of 6 °C say about the range of weather conditions?
# - What information is missing that the range does not provide?

Task 4

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# Task 4: Sample variance of dice rolls
# We have 5 dice results, calculate the variance, and interpret it.
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# 1. Create the dataset
rolls <- c(3, 6, 2, 5, 4) # Vector 'rolls' with five results

# 2. Display the values
rolls # Display all five die rolls
#> [1] 3 6 2 5 4

# 3. Calculate the sample variance
var(rolls) # Variance of the five results
#> [1] 2.5

# Interpretation questions:
# - What does a variance of 2.5 mean in the context of dice?
# - How would the variance change if one result were 6 instead of 2?

Task 5

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# Exercise 5: Boxplot of salaries
# We consider 6 monthly salaries, summarize them statistically, and visualize them.
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# 1. Create dataset
salary <- c(45, 50, 55, 60, 48, 52) # Monthly salaries (in k€) of 6 people

# 2. Descriptive statistics
summary(salary) # Min, 1st Qu., Median, Mean, 3rd Qu., Max
#> Min. 1st Qu. Median Mean 3rd Qu. Max.
#> 45.00 48.00 51.00 51.67 55.00 60.00

# 3. Create boxplot
boxplot(salary, main="Monthly salaries", ylab="k€") # Boxplot with labels
# (graphically in the Plots window)

# Questions for interpretation:
# - What values do the median and quartiles provide?
# - Are there any outliers, and what would you do with them?