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The following table shows the distribution of the heights of a group of factory workers :

Ht. (cm)No. of workers
150 - 1556
155 - 16012
160 - 16518
165 - 17020
170 - 17513
175 - 1808
180 - 1856

(i) Determine the cumulative frequencies.

(ii) Draw the 'less than' cumulative frequency curve on graph paper.

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Answer

(i) The cumulative frequency distribution table is as follows :

Ht. (cm)No. of workersCumulative frequency
150 - 15566
155 - 1601218 (6 + 12)
160 - 1651836 (18 + 18)
165 - 1702056 (36 + 20)
170 - 1751369 (56 + 13)
175 - 180877 (69 + 8)
180 - 185683 (77 + 6)

(ii) Steps for construction of 'less than' cumulative frequency curve :

  1. Since, the scale on x-axis starts at 150, a break (kink) is shown near the origin on x-axis to indicate that the graph is drawn to scale beginning at 150.

  2. Take 2 cm along x-axis = 5 cm.

  3. Take 1 cm along y-axis = 10 workers.

  4. Ogive always starts from a point on x-axis representing the lower limit of first class. Mark point (150, 0).

  5. Take upper class limits along x-axis, corresponding cumulative frequencies along y-axis, mark the points (155, 6), (160, 18), (165, 36), (170, 56), (175, 69), (180, 77) and (185, 83).

  6. Join the points marked by a free hand curve.

The required ogive is shown in the below figure:

The following table shows the distribution of the heights of a group of factory workers. (i)Determine the cumulative frequencies. (ii) Draw the 'less than' cumulative frequency curve on graph paper. Graphical Representation, Concise Mathematics Solutions ICSE Class 10.

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