8. The following data gives the information on the observed lifetimes (in hours) of $225$ electrical components:
8. The following data gives the information on the observed lifetimes (in hours) of $225$ electrical components:
Lifetimes (in hours):0 – 2020 – 4040 – 6060 – 8080 – 100100 – 120
No. of components:          103552613829

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

R D Sharma Solutions For Class 10 Maths Chapter 7 Statistics ex 7.5 - 10

Mode

Thus, the modal lifetime of electrical components is $65.625$hours