Q3 of 26 Page 245

The relative humidity (in %) of a certain city for a month of 30 days was as follows:

98.1 98.6 99.2 90.3 86.5 95.3 92.9 96.3 94.2 95.1


89.2 92.3 97.1 93.5 92.7 95.1 97.2 93.3 95.2 97.3


96.2 92.1 84.9 90.2 95.7 98.3 97.3 96.1 92.1 89


(i) Construct a grouped frequency distribution table with classes 84 - 86, 86 - 88, etc.


(ii) Which month or season do you think this data is about?


(iii) What is the range of this data?

(i) The given data is very large. Therefore, we will be construct a group frequency of class size 2.

Therefore,


Class interval will be:


84 – 86, 86 – 88, 88 – 90, 90 – 92 and so on.


The data is represented in the table as:












































RELATIVE HUMIDITY (in %)



FREQUENCY



84-86



1



86-88



1



88-90



2



90-92



2



92-94



7



94-96



6



96-98



7



98-100



4



Total



30



(ii) The humidity is very high in the data which is observed during rainy season. Hence, it must be rainy season.


(iii) Range of data = Maximum value of data – Minimum value of data


= 99.2 – 84.9


= 14.3


More from this chapter

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1

The blood groups of 30 students of Class VIII are recorded as follows:

A, B, O, O, AB, O, A, O, B, A, O, B, A, O, O,


A, AB, O, A, A, O, O, AB, B, A, O, B, A, B, O


Represent this data in the form of a frequency distribution table. Which is the most common, and which is the rarest, blood group among these students?

 2

The distance (in km) of 40 engineers from their residence to their place of work were found as follows:

5 3 10 20 25 11 13 7 12 31


19 10 12 17 18 11 32 17 16 2


7 9 7 8 3 5 12 15 18 3


12 14 2 9 6 15 15 7 6 12


Construct a grouped frequency distribution table with class size 5 for the data given above taking the first interval as 0-5 (5 not included). What main features do you observe from this tabular representation?

 4

The heights of 50 students, measured to the nearest centimetres, have been found to be as follows:

161 150 154 165 168 161 154 162 150 151

162 164 171 165 158 154 156 172 160 170

153 159 161 170 162 165 166 168 165 164

154 152 153 156 158 162 160 161 173 166

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 160 - 165, 165 - 170, etc.

(ii) What can you conclude about their heights from the table?

 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


(i) Make a grouped frequency distribution table for this data with class intervals as0.00 - 0.04, 0.04 - 0.08, and so on.


(ii) For how many days, was the concentration of sulphur dioxide more than 0.11parts per million?