Draw a frequency curve for the data given below:
`{:("Class Interval",0-10,10-20,20-30,30-40,40-50,50-60,60-70),("Frequency",3,2,4,6,9,7,10):}`

Explanation

Following table shows the mid-values of classes and corresponding frequencies for the given data:
`{:("Class Interval","Mid-value","Frequency"),(" "0-10," "5," "3),(" "10-20," "15," "2),(" "20-30," "25," "4),(" "30-40," "35," "6),(" "40-50," "45," "9),(" "50-60," "55," "7),(" "60-70," "65," "10):}`
Now, taking the mid-values of the classes along the X-axis and the corresponding frequencies along the Y-axis, we mark the points obtained from the above table in a graph sheet and join them with a smooth curve, which gives the frequency curve as shown in the Fig. 9.4.