Determine the modal lifetimes of the components.

Question

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

Determine the modal lifetimes of the components.

Answer 1

Since the maximum frequency 61 is in the class 60 – 80, this is the required modal class. 

Modal class frequency, f₁ = 61. 

Frequency of the class preceding the modal class f₀ = 52 

Frequency of the class succeeding the modal class f₂ = 38 

Lower boundary of the modal class, l = 60 

Height of the class, h = 20

= 60 + \(\frac{9}{32}\) × 20 

= 60 + 5.625 

= 65.625 hours.