# Ex.14.2 Q8 Statistics Solution - NCERT Maths Class 9

## 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 ’\(15-20\)’)