Observe the frequency polygon (marks vs students) through (25, 0), (35, 20), (45, 40), (55, 50), (65, 60), (75, 35), (85, 15), (95, 0) and answer the questions on classes, class marks and frequencies.

Question

Observe the following frequency polygon and write the answers of the questions below it. (Frequency polygon, fig 6.6: X-axis – Marks, Y-axis – Students. Scale: X-axis 1 cm = 2 marks, Y-axis 1 cm = 10 students. The polygon starts on the X-axis at 25, passes through the points (35, 20), (45, 40), (55, 50), (65, 60), (75, 35), (85, 15) and ends on the X-axis at 95. The X-axis is marked 20, 30, 40, ..., 100.) (1) Which class has the maximum number of students? (2) Write the classes having zero frequency. (3) What is the class-mark of the class, having frequency of 50 students? (4) Write the lower and upper class limits of the class whose class mark is 85. (5) How many students are in the class 80-90?

Doubtly AI · Answer

Answer: (1) 60–70 (2) 20–30 and 90–100 (3) 55 (4) 80 and 90 (5) 15 Each plotted point is (class mark, frequency) and the class width is 10, so the class mark 35 stands for the class 30–40, 45 for 40–50, and so on. (1) The highest point is (65, 60), so the class 60–70 has the maximum number of students (60). (2) The polygon touches the X-axis at 25 and 95, the class marks of 20–30 and 90–100; these classes have zero frequency. (3) The point (55, 50) shows frequency 50, so the class mark is 55. (4) Class mark 85 belongs to the class 80–90: lower limit 80, upper limit 90. (5) The point (85, 15) shows 15 students in the class 80–90.

Observe the frequency polygon (marks vs students) through (25, 0), (35, 20), (45, 40), (55, 50), (65, 60), (75, 35), (85, 15), (95, 0) and answer the questions on classes, class marks and frequencies.

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