Ex.14.2 Q9 Statistics Solution - NCERT Maths Class 9

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Question

A company manufactures car batteries of a particular type. The lives (in years) of \(40\) such batteries were recorded as follows:

\(2.6\) \(3.0\) \(3.7\) \(3.2\) \(2.2\) \(4.1\) \(3.5\) \(4.5\)
\(3.5\) \(2.3\) \(3.2\) \(3.4\) \(3.8\) \(3.2\) \(4.6\) \(3.7\)
\(2.5\) \(4.4\) \(3.4\) \(3.3\) \(2.9\) \(3.0\) \(4.3\) \(2.8\)
\(3.5\) \(3.2\) \(3.9\) \(3.2\) \(3.2\) \(3.1\) \(3.7\) \(3.4\)
\(4.6\) \(3.8\) \(3.2\) \(2.6\) \(3.5\) \(4.2\) \(2.9\) \(3.6\)

Construct a grouped frequency distribution table for this data, using class Intervals of size \(0.5\) starting from the interval \(2 - 2.5.\)

Text Solution

 

What is known?

  • The life span (in years) of \(40\) car batteries manufactured by a company.
  • Class size is ‘\(0.5\)
  • A class interval such as \(2-2.5\)

What is unknown?

  • Constructing a grouped frequency distribution table with a class size of \(0.5.\)

Steps:

The required grouped frequency distribution table can be constructed as follows, with class intervals of ‘\(2-2.5\)’, ‘\(2.5-3\)’, ‘\(3-3.5\)’, ‘\(3.5-4\)’, and so on.

LIFE SPAN OF BATTERIES (in years) NUMBER OF BATTERIES (frequency)
\(2-2.5 \) \(2\)
\(2.5-3.0 \) \(6 \)
\(3.0-3.5\) \(14 \)
\(3.5-4.0 \) \(11 \)
\(4.0-4.5 \) \(4 \)
\(4.5-5.0\) \(3\)
TOTAL \(40\)

 

  
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