Practice Application To Grouped Data (5) - Standard Deviation & Variance

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9 questions

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3 cards from this section. Quick, good the night before a test.
Exercise
6 questions · about 4 min · pass mark 70%. Hints available.
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3 questions · about 2 min · pass mark 70%. Hints available.
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6 sample questions

Question 1.
What is the midpoint of the class interval 20-30?
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Add the lower and upper limits and divide by 2.
Question 2.
If a class has a frequency of 4 and a midpoint of 15, what is fx?
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Multiply frequency by midpoint.
3Question 3.
What is the formula for calculating the mean of grouped data?
- a) Mean = Σf / n
- b) Mean = Σ(f * x) / Σf
- c) Mean = Σ(x - x̄)²
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Think about the values we are summing and dividing by.
4Question 4.
True or False: The standard deviation can be negative.
- True
- False
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What does standard deviation represent?
Question 5.
A fruit vendor records the weights of bags: 1-3 kg (5), 3-5 kg (10), 5-7 kg (15). Determine the mean and standard deviation of the weights.
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Follow through with midpoints and properly calculate deviations.
Question 6.
In a survey, ages are grouped as follows: 0-20 (4), 21-40 (6), 41-60 (10). Find the variance of the ages.
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Don't forget to use midpoints and find squared differences.

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