Statistics
Karnataka Board · Class 9 · Mathematics
Flashcards for Statistics — Karnataka Board Class 9 Mathematics. Quick Q&A cards covering key concepts, definitions, and formulas.
Draw a bar graph for this data: Mathematics scores - 15 students scored 80-90, 12 students scored 70-80, 8 students scored 60-70, 5 students scored 50-60. What scale would you choose for the y-axis?
Answer
Step 1: Identify variables - x-axis: Score ranges, y-axis: Number of students. Step 2: Choose scale - Maximum frequency = 15, so choose 1 unit = 2 students (y-axis goes 0,2,4,6,8,10,12,14,16). Step 3:
Find the class-mark for the interval 25-35. Then calculate class-marks for: 10-20, 45-55, 60-80.
Answer
Formula: Class-mark = (Upper limit + Lower limit) ÷ 2. Step 1: For 25-35: (35 + 25) ÷ 2 = 60 ÷ 2 = 30. Step 2: For 10-20: (20 + 10) ÷ 2 = 15. Step 3: For 45-55: (55 + 45) ÷ 2 = 50. Step 4: For 60-80:
Create a histogram for: Height (cm): 140-150 (5 students), 150-160 (12 students), 160-170 (18 students), 170-180 (8 students), 180-190 (2 students). All intervals have equal width - what's special abo
Answer
Since all class intervals have equal width (10 cm), we can directly use frequencies as heights. Step 1: Draw x-axis for height ranges, y-axis for frequency. Step 2: Choose scale (max frequency = 18, u
Solve this varying width histogram problem: Class intervals: 0-10 (freq=4), 10-30 (freq=8), 30-50 (freq=12), 50-100 (freq=10). Find the height of each rectangle if minimum class width is used as refer
Answer
Step 1: Find minimum class width = 10. Step 2: Calculate rectangle heights using formula: Height = (Frequency/Class width) × Minimum width. Step 3: For 0-10: (4/10) × 10 = 4. Step 4: For 10-30: (8/20)
From this frequency table, create the coordinates for a frequency polygon: Marks: 0-20(3), 20-40(7), 40-60(12), 60-80(5), 80-100(1). Include the end points.
Answer
Step 1: Find class-marks: 10, 30, 50, 70, 90. Step 2: Add imaginary classes before and after with zero frequency. Before: (-20)-0, class-mark = -10. After: 100-120, class-mark = 110. Step 3: Coordinat
A histogram shows test scores. The bar for 70-80 has height 15, width 10. The bar for 80-100 has height 8, width 20. Which score range actually has more students and why?
Answer
Step 1: Remember that frequency = area of rectangle (not height). Step 2: For 70-80: Area = height × width = 15 × 10 = 150. Step 3: For 80-100: Area = 8 × 20 = 160. Step 4: Since 160 > 150, the range
When should you use a bar graph vs. a histogram? Give the deciding factors and one example each.
Answer
Use Bar Graph when: Data has discrete/separate categories. Example: Favorite subjects - Math(20), Science(15), English(10), Hindi(8). Use Histogram when: Data has continuous intervals. Example: Studen
Convert this data to make it suitable for a histogram: Student ages: 13, 14, 14, 15, 15, 15, 16, 16, 17, 17, 17, 17, 18, 18, 19. Create 3 equal class intervals.
Answer
Step 1: Find range = 19 - 13 = 6. Step 2: Create 3 intervals: 13-15, 15-17, 17-19. Step 3: Count frequencies (include lower limit, exclude upper): 13-15: {13,14,14,15,15,15} = 6 students. 15-17: {16,1
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What are the important topics in Statistics for Karnataka Board Class 9 Mathematics?
Statistics covers several key topics that are frequently asked in Karnataka Board Class 9 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
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There are 20 flashcards for Statistics covering key definitions, formulas, and concepts. Use them daily for 10–15 minutes for best results.
Sources & Official References
- Karnataka SSLC — kseeb.kar.nic.in
- Dept of Pre-University Education, Karnataka
- 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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