# NCERT Class 9 Solutions: Statistics (Chapter 14) Exercise 14.2-Part 2 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Q-4 The heights of 46 students, measured to the nearest centimeters, have been found to be as follows:

150 154 165 168 161 154 162 150 151 164 171 165 158 154 156 172 160 170 159

161 170 162 165 166 168 165 164 152 153 156 158 162 160 161 173 166 161 159

162 167 168 159 158 153 154 159

I. Represent the data given above by a grouped frequency distribution table, taking the class intervals as , etc.

II. What can you conclude about their heights from the table?

Solution (i) :

- A grouped frequency distribution table has to be constructed class intervals etc.
- By observing the data, the required table can be constructed below:

Heights (in cm) | Frequency |

Total |

Solution (ii) :

We can conclude that more than 50 % of student are shorter then 165cm.

Q-5 A study was conducted to find out the concentration of sulphur dioxide in the air in Parts per million (ppm) of a certain city. The data obtained for 30 days is as follows:

0.03 0.08 0.08 0.09 0.04 0.17 0.16 0.05 0.02 0.06 0.18 0.20 0.11 0.08 0.12 0.13

0.22 0.07 0.08 0.01 0.10 0.06 0.09 0.18 0.11 0.07 0.05 0.07 0.01 0.04

1. Make a grouped frequency distribution table for this data with class intervals as and so on.

2. For how many days, was the concentration of sulphur dioxide more than 0.11 parts per million?

Solution (1) :

- The minimum and maximum concentration of sulphur dioxide in the air in parts per million is 0.01 and 0.22 respectively.
- It is given , one of the class intervals and the class size in the same

So the classes of equal size are:

Distribution table below is given below:

Solution (2) :

The sulphur dioxide was more than 0.11 ppm for 8 days.

Q-6 Three coins were tossed 30 times simultaneously. Each time the number of heads occurring was noted down as follows:

0 1 2 2 1 2 3 1 3 0 3 1 1 2 2 0 1 2 1 3 0 0 1 1 2 3 2 2 0 1

Prepare a frequency distribution table for the data given above.

Solution:

Given above data, the required frequency distribution table can be constructed as below:

Number of heads | Number of time (frequency) |

0 | 6 |

1 | 10 |

2 | 9 |

3 | 5 |

Total | 30 |