2. The following data gives the information on the observed lifetimes (in hours) of 225 electrical components :
Determine the modal lifetimes of the components.
The class having maximum frequency is the modal class.
The maximum frequency is 61 and hence the modal class = 60-80
Lower limit (l) of modal class = 60, class size (h) = 20
Frequency ( ) of the modal class = 61 frequency ( ) of class preceding the modal class = 52, frequency ( ) of class succeeding the modal class = 38.
Thus, the modal lifetime of 225 electrical components is 65.62 hours