The following data is gives the information on the observed lifetimes (in hours) of 225 electrical components:

Here, the maximum frequency of electrical components is 61 so the modal class is 60−80.

Therefore,

$l=60$

$h=20$

$f=61$

$f_{1}=52$

$f_{2}=38$

$\Rightarrow$ Mode $=l+\frac{f-f_{1}}{2 f-f_{1}-f_{2}} \times h$

$=60+\frac{61-52}{122-52-38} \times 20$

$=60+\frac{9}{32} \times 20$

Mode $=65.625 \mathrm{hrs}$

Thus, the modal lifetimes of the components is 65.625 hours.