Class 9 Bar Graphs and Histograms — practice questions with answers
Statistics and Probability · 5 sample questions from the school syllabus. Try each one, then open the answer and the worked solution.
1. In a bar graph, what does the height (length) of each bar represent?
AThe frequency or value of the category
BThe width of the class
CThe number of bars
DThe class mark
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Answer: A) The frequency or value of the category
In a bar graph each bar's length is proportional to the value or frequency of the category it represents.
2. Class marks of two consecutive equal classes are 15 and 25. The common class size (width) is:
A20
B11
C9
D10
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Answer: D) 10
The difference between consecutive class marks equals the class size: 25 - 15 = 10.
3. Meena prepared a pictograph of biscuits sold in a week where 1 picture = 12 biscuits. Monday had 5 pictures and Tuesday had 4 pictures. How many more biscuits were sold on Monday than on Tuesday?
4. In a histogram of test scores, the class 60-70 has frequency 12 and the class 70-80 has frequency 18. In a frequency polygon, the point for the class 70-80 is plotted at:
A(75, 18)
B(70, 18)
C(80, 18)
D(75, 12)
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Answer: A) (75, 18)
A frequency polygon point uses (class mark, frequency). Class mark of 70-80 = 75, frequency = 18, giving (75, 18).
5. A histogram of exam marks has classes 0-20, 20-40, 40-60, 60-80, 80-100. The frequencies form an arithmetic progression and their sum is 40. The class 0-20 has frequency 4 and the class 80-100 has frequency 12. What is the frequency of the middle class 40-60?
A9
B8
C16
D7
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Answer: B) 8
An AP with first term 4 and last term 12 has middle (third) term = (4 + 12)/2 = 8. Check: terms 4,6,8,10,12 sum to 40, consistent.