Averages from grouped data (Edexcel GCSE Statistics): Flashcards
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Practise the cards
10 cards from this deck
How do you estimate the mean from grouped data?
How do you estimate the mean from grouped data?
Use the formula: Mean = Σfx ÷ Σf, with midpoints.
What is the formula for the mean from grouped data?
What is the formula for the mean from grouped data?
Mean = Σfx ÷ Σf where f = frequency, x = midpoint.
How is a midpoint calculated for a class interval?
How is a midpoint calculated for a class interval?
Midpoint = (lower + upper) ÷ 2 of the class interval.
What is the step to find fx in grouped data?
What is the step to find fx in grouped data?
Multiply the frequency (f) by the midpoint (x) for each interval.
Why might the mean from grouped data be inaccurate?
Why might the mean from grouped data be inaccurate?
Values within groups may not be evenly spread; it’s an estimate.
What should you do after calculating Σfx and Σf?
What should you do after calculating Σfx and Σf?
Divide Σfx by Σf for the estimated mean.
Why do the data assumptions matter in estimating the mean?
Why do the data assumptions matter in estimating the mean?
They impact accuracy; assumptions about distribution affect results.
In what form is the calculated mean often presented?
In what form is the calculated mean often presented?
It is often denoted as x̄ (x bar) in statistical notation.
Find mean: 5-15(6),15-25(9),25-45(5)
Find mean: 5-15(6),15-25(9),25-45(5)
Midpoints 10,20,35; Σfx=415, Σf=20; mean=20.75
Find mean: 0-10(8),10-20(12),20-30(14),30-40(11),40-50(5)
Find mean: 0-10(8),10-20(12),20-30(14),30-40(11),40-50(5)
Mean ≈ 23.6 years