Tales by Dots and Lines
CBSE · Class 8 · Mathematics
All formulas from Tales by Dots and Lines in CBSE Class 8 Mathematics. Key equations, constants, and identities for board exam preparation.
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Formulas
1. Mean and Median Basics
(x1 + x2 + x3 + ... + xn) / n = a
Average of 3 and 7 = 5
2. Effect of Changing Data
((x1 + 3) + (x2 + 3) + (x3 + 3) + ... + (xn + 3)) / n = a + 3
((5x1) + (5x2) + (5x3) + ... + (5xn)) / n = 5a
3. Finding the Unknown
Average weight of the players = Sum of weight of all players / Number of players
349 + w = 392
w = 392 - 349 = 43
4. Mean and Median with Frequencies
average = Sum of all the values in the data / Number of values in the data
((3 × 3) + (4 × 11) + (5 × 9) + (6 × 7) + (7 × 3) + (8 × 1) + (9 × 1) + (10 × 1)) / (3 + 11 + 9 + 7 + 3 + 1 + 1 + 1) = 188 / 36 = 5.22
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Sources & Official References
- NCERT Official — ncert.nic.in
- CBSE Academic — cbseacademic.nic.in
- CBSE Official — cbse.gov.in
- National Education Policy 2020 — education.gov.in
Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.
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