$A$ 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:
$\begin{array}{llllll}0.03 & 0.08 & 0.08 & 0.09 & 0.04 & 0.17 \\ 0.16 & 0.05 & 0.02 & 0.06 & 0.18 & 0.20 \\ 0.11 & 0.08 & 0.12 & 0.13 & 0.22 & 0.07 \\ 0.08 & 0.01 & 0.10 & 0.06 & 0.09 & 0.18 \\ 0.11 & 0.07 & 0.05 & 0.07 & 0.01 & 0.04\end{array}$
$(i)$ Make a grouped frequency distribution table for this data with class intervals as $0.00 - 0.04, 0.04 - 0.08$,and so on.
$(ii)$ For how many days was the concentration of sulphur dioxide more than $0.11$ parts per million?
$\begin{array}{llllll}0.03 & 0.08 & 0.08 & 0.09 & 0.04 & 0.17 \\ 0.16 & 0.05 & 0.02 & 0.06 & 0.18 & 0.20 \\ 0.11 & 0.08 & 0.12 & 0.13 & 0.22 & 0.07 \\ 0.08 & 0.01 & 0.10 & 0.06 & 0.09 & 0.18 \\ 0.11 & 0.07 & 0.05 & 0.07 & 0.01 & 0.04\end{array}$
$(i)$ Make a grouped frequency distribution table for this data with class intervals as $0.00 - 0.04, 0.04 - 0.08$,and so on.
$(ii)$ For how many days was the concentration of sulphur dioxide more than $0.11$ parts per million?
(8) To construct the grouped frequency distribution table,we count the number of observations falling into each class interval. Note that the upper limit of each class is excluded from that class.
$(ii)$ The number of days for which the concentration of $SO_2$ is more than $0.11$ $ppm$ corresponds to the sum of frequencies for the intervals $0.12 - 0.16, 0.16 - 0.20$,and $0.20 - 0.24$.
Required number of days $= 2 + 4 + 2 = 8$.
Therefore,for $8$ days,the concentration of $SO_2$ was more than $0.11$ $ppm$.
| Concentration of $SO_2$ (in $ppm$) | Number of days (frequency) |
| $0.00 - 0.04$ | $4$ |
| $0.04 - 0.08$ | $9$ |
| $0.08 - 0.12$ | $9$ |
| $0.12 - 0.16$ | $2$ |
| $0.16 - 0.20$ | $4$ |
| $0.20 - 0.24$ | $2$ |
| Total | $30$ |
$(ii)$ The number of days for which the concentration of $SO_2$ is more than $0.11$ $ppm$ corresponds to the sum of frequencies for the intervals $0.12 - 0.16, 0.16 - 0.20$,and $0.20 - 0.24$.
Required number of days $= 2 + 4 + 2 = 8$.
Therefore,for $8$ days,the concentration of $SO_2$ was more than $0.11$ $ppm$.
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Similar Questions
$A$ teacher wanted to analyze the performance of two sections of students in a mathematics test of $100$ marks. Looking at their performances,she found that a few students got under $20$ marks and a few got $70$ marks or above. So she decided to group them into intervals of varying sizes as follows: $0-20, 20-30, ..., 60-70, 70-100$. Then she formed the following table:
Marks Number of students $0-20$ $7$ $20-30$ $10$ $30-40$ $10$ $40-50$ $20$ $50-60$ $20$ $60-70$ $15$ $70-100$ $8$ Total $90$
$A$ histogram for this table was prepared by a student as shown in Fig. Carefully examine this graphical representation. Do you think that it correctly represents the data?
| Marks | Number of students |
| $0-20$ | $7$ |
| $20-30$ | $10$ |
| $30-40$ | $10$ |
| $40-50$ | $20$ |
| $50-60$ | $20$ |
| $60-70$ | $15$ |
| $70-100$ | $8$ |
| Total | $90$ |
$A$ histogram for this table was prepared by a student as shown in Fig. Carefully examine this graphical representation. Do you think that it correctly represents the data?
Medium
View SolutionLet us consider the following frequency distribution table which gives the weights of $38$ students of a class:
Weights (in $kg$) Number of students $31-35$ $9$ $36-40$ $5$ $41-45$ $14$ $46-50$ $3$ $51-55$ $1$ $56-60$ $2$ $61-65$ $2$ $66-70$ $1$ $71-75$ $1$ Total $38$
If two new students of weights $35.5\, kg$ and $40.5\, kg$ are admitted to this class,how should the frequency distribution table be adjusted to include them?
| Weights (in $kg$) | Number of students |
| $31-35$ | $9$ |
| $36-40$ | $5$ |
| $41-45$ | $14$ |
| $46-50$ | $3$ |
| $51-55$ | $1$ |
| $56-60$ | $2$ |
| $61-65$ | $2$ |
| $66-70$ | $1$ |
| $71-75$ | $1$ |
| Total | $38$ |
If two new students of weights $35.5\, kg$ and $40.5\, kg$ are admitted to this class,how should the frequency distribution table be adjusted to include them?
Difficult
View SolutionThe following table gives the life times of $400$ neon lamps:
The time (in hours) Number of lamps $300-400$ $14$ $400-500$ $56$ $500-600$ $60$ $600-700$ $86$ $700-800$ $74$ $800-900$ $62$ $900-1000$ $48$
$(i)$ Represent the given information with the help of a histogram.
$(ii)$ How many lamps have a life time of more than $700$ hours?
| The time (in hours) | Number of lamps |
| $300-400$ | $14$ |
| $400-500$ | $56$ |
| $500-600$ | $60$ |
| $600-700$ | $86$ |
| $700-800$ | $74$ |
| $800-900$ | $62$ |
| $900-1000$ | $48$ |
$(i)$ Represent the given information with the help of a histogram.
$(ii)$ How many lamps have a life time of more than $700$ hours?
Medium
View SolutionConsider the marks obtained by $10$ students in a mathematics test as given below:
$55, 36, 95, 73, 60, 42, 25, 78, 75, 62$
$55, 36, 95, 73, 60, 42, 25, 78, 75, 62$
Easy
View SolutionFind the mode of $14, 25, 14, 28, 18, 17, 18, 14, 23, 22, 14, 18.$
Easy
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