- A3
- B4
- C2
- D1
Step-by-Step Solution
Only Tuesday (7) and Thursday (9) rise above 4, so the answer is 2 days. Monday is exactly 4, which is not more than 4.
Answer: C) 2
A bar graph shows the number of library books issued on each day of a week. The bar heights are Mon 4, Tue 7, Wed 3, Thu 9, Fri 2. On how many days were more than 4 books issued?
Class 9StatisticsStatistics and Probability
Key idea: Histogram vs bar graph
Both look like bars, but they differ:
**Bar graph**: For DISCRETE / categorical data (favourite colour, sport, etc.). Bars have GAPS between them. Width has no meaning.
**Histogram**: For CONTINUOUS / grouped data with class intervals. Bars TOUCH (no gaps), reflecting that the class boundaries are continuous. Bar WIDTH represents class size; HEIGHT represents frequency.
**Frequency polygon**: connect the midpoints (class marks) of the tops of histogram bars to form a line graph. Useful for comparing two distributions on the same axes.
**Key rule**: histogram bars must have no gaps; bar graph bars MUST have gaps.
**Bar graph**: For DISCRETE / categorical data (favourite colour, sport, etc.). Bars have GAPS between them. Width has no meaning.
**Histogram**: For CONTINUOUS / grouped data with class intervals. Bars TOUCH (no gaps), reflecting that the class boundaries are continuous. Bar WIDTH represents class size; HEIGHT represents frequency.
**Frequency polygon**: connect the midpoints (class marks) of the tops of histogram bars to form a line graph. Useful for comparing two distributions on the same axes.
**Key rule**: histogram bars must have no gaps; bar graph bars MUST have gaps.
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