# 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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