Ex.14.2 Q8 Statistics Solution - NCERT Maths Class 9

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Question

Thirty children were asked about the number of hours they watched TV Programmes in the previous week. The results were found as follows:

\[\begin{align}1\,\,\,\, 6\,\,\,\, 2\,\,\,\, 3\,\,\,\, 5\,\,\,\, 12\,\,\,\, 5\,\,\,\, 8\,\,\,\, 4\,\,\,\, 8\,\,\,\, \\10\,\,\,\, 3\,\,\,\, 4\,\,\,\, 12\,\,\,\, 2\,\,\,\, 8\,\,\,\, 15\,\,\,\, 1\,\,\,\, 17\,\,\,\, 6\,\,\,\, \\3\,\,\,\, 2\,\,\,\, 8\,\,\,\, 5\,\,\,\, 9\,\,\,\, 6\,\,\,\, 8\,\,\,\, 7\,\,\,\, 14\,\,\,\, 12\,\,\,\,\end{align}\]

(i) Make a grouped frequency distribution table for this data, taking class width \(5\) and one of the class intervals as \(5 - 10.\)

(ii) How many children watched television for \(15\) or more hours a week?

Text Solution

 

What is known?

  • Number of hours of watching TV programs by \(30\) children in a weak.
  • Class width ‘\(5\)
  • A Class interval, such as \(5-10\)

What is unknown?

  • A grouped frequency distribution table with a class width of ‘\(5\)
  • Number of children who watched television for \(15\) or more hours per weak

Steps:

A grouped frequency distribution table can be constructed as follows with the class intervals of \(0-5, 5-10, 10-15, 15-20\) and so on.

HOURS NUMBERS OF CHILDREN (frequency)
\(0-5 \) \(10\)
\(5-10 \) \(13\)
\(10-15 \) \(5 \)
\(15-20\) \(2\)
TOTAL \(30\)

We can observe from the table, that the number of children who watched television for \(15\) or more hours a week is \(2\) (which falls under the class interval ’\(15-20\)’)

  
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