Question

The following data given the information on the observed life terms (in hours) of $200$ electrical components.

Life times (in hours)	40-60	60-80	80-100	100-120	120-140	140-160
Frequency	$25$	$38$	$65$	$24$	$31$	$17$

Determine the modal lifetimes of the components.

Answer 1

Life time	Frequency
40-60	25
60-80	38
80-100	65
100-120	24
120-140	31
140-160	17

Class size $h=20$

$l=60$

$f=65$

$f_1=38$

$f_2=24$

$Mode=l+\frac{f_1-f_2}{2f-f_1-f_2}\times hM=60+\frac{38-24}{2\left(65\right)-28-24}\times 20M=60+3.58M=63.58$