Question 3.31: Find the modal class and modal value for the frequency distr...
Find the modal class and modal value for the frequency distribution of the heights of adults that were given in the table in Example 3.26.
Referring back to the table, it is easy to see that the class of heights which occurs most frequently is 175 – 179 cm. This occurs 45 times.
Now, to find the modal value, we need to produce a histogram for the data. We did this for Example 3.27. This histogram is shown again here, this time with the modal value shown.
From Figure 3.25 it can be seen that the modal value = 178.25 ± 0.5 cm.
This value is obtained from the intersection of the two construction lines, AB and CD. The line AB is drawn diagonally from the highest value of the preceding class up to the top right-hand corner of the modal class. The line CD is drawn from the top left-hand corner of the modal group to the lowest value of the next class immediately above the modal group. Then, as can be seen, the modal value is read-off where the projection line meets the x-axis.
