Standard deviation (Edexcel GCSE Statistics): Quizzes
📚Quizzes
Practise the questions
10 questions from this quiz
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Practise the questions
10 questions from this quiz
What is the formula for the standard deviation of grouped data?
What is the formula for the standard deviation of grouped data?
√(Σfx²/Σf) - (Σfx/Σf)²
In a grouped data example, the total frequency was 40, and Σf×Mid was 1820. What was the mean?
In a grouped data example, the total frequency was 40, and Σf×Mid was 1820. What was the mean?
45.5 seconds
Why is the calculated SD only an estimate?
Why is the calculated SD only an estimate?
Midpoints represent all data
When calculating the standard deviation, what is the last step?
When calculating the standard deviation, what is the last step?
Take the square root
In the puzzles example, the total sum of f×Mid² was 104800. If total f is 40, what is the variance estimate?
In the puzzles example, the total sum of f×Mid² was 104800. If total f is 40, what is the variance estimate?
549.75
What does a larger SD indicate in grouped data?
What does a larger SD indicate in grouped data?
More spread
What is the main advantage of understanding the estimation process in grouping?
What is the main advantage of understanding the estimation process in grouping?
Better understanding of data
Classes 0–10 (f=4), 10–20 (f=6), 20–30 (f=10). Find estimated SD (2 dp).
Classes 0–10 (f=4), 10–20 (f=6), 20–30 (f=10). Find estimated SD (2 dp).
7.81
For class 30 < x ≤ 50 with frequency 8, what is f × midpoint²?
For class 30 < x ≤ 50 with frequency 8, what is f × midpoint²?
12800
Given ∑f=60, ∑fD=2440, ∑fD²=145200. Find SD to 3 s.f.
Given ∑f=60, ∑fD=2440, ∑fD²=145200. Find SD to 3 s.f.
27.7