Lifetimes (in hours): | 0 – 20 | 20 – 40 | 40 – 60 | 60 – 80 | 80 – 100 | 100 – 120 |
No. of components: | 10 | 35 | 52 | 61 | 38 | 29 |
Solution:
Statistics is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a scientific, industrial, or social problem, it is conventional to begin with a statistical population or a statistical model to be studied.
From the data given as above its observed that maximum class frequency is $61$ which belongs to class interval $60 – 80$.
So, modal class limit (l) of modal class $= 60$
Frequency (f) of modal class $= 61$
Frequency (f1) of class preceding the modal class $= 52$
Frequency (f2) of class succeeding the modal class $= 38$
Class size (h) $= 20$
Using the formula for find mode, we have
Mode
Thus, the modal lifetime of electrical components is $65.625$hours