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प्रश्न
Which of the two – the primary or the secondary data – is more reliable and why?
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उत्तर
The word data means information statistical data and of two types
(i) Primary data, (ii) Secondary data
Primary data are reliable and relevant because they are original in character and are collected by some individuals or by research bodies.
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संबंधित प्रश्न
What do you understand by the word “statistics” in
(i) Singular form
(ii) Plural form?
Explain the meaning of the term Class-size.
Explain the meaning of the term Frequency.
Find the mean, median and mode of the following data:
| Marks obtained | 25 – 35 | 35 – 45 | 45 – 55 | 55 – 65 | 65 – 75 | 75 – 85 |
| No. of students | 7 | 31 | 33 | 17 | 11 | 1 |
A survey regarding the heights (in cm) of 50 girls of a class was conducted and the following data was obtained:
| Height (in cm) | 120 – 130 | 130 – 140 | 140 – 150 | 150 – 160 | 160 – 170 | Total |
| No. of girls | 2 | 8 | 12 | 20 | 8 | 50 |
Find the mean, median and mode of the above data.
For a certain distribution, mode and median were found to be 1000 and 1250 respectively. Find mean for this distribution using an empirical relation.
The median of 19 observations is 30. Two more observations are made and the values of these are 8 and 32. Find the median of the 21 observations taken together.
| HINT | Since 8 is less than 30 and 32 is more than 30, so the value of median (middle value) remains unchanged. |
If the median of `x/5, x/4, x/2, x and x/3`, where x > 0, is 8, find the value of x.
| HINT | Arranging the observations in ascending order, we have `x/5, x/4, x/3, x/2, x` Median `= x/3 = 8.` |
The time, in seconds, taken by 150 athletes to run a 100 m hurdle race are tabulated below:
| Time (sec.) | 13 – 14 | 14 – 15 | 15 – 16 | 16 – 17 | 17 – 18 | 18 – 19 |
| Number of Athletes | 2 | 4 | 5 | 71 | 48 | 20 |
The number of athletes who completed the race in less than 17 seconds is:
The Empirical relation between the three measures of central tendency is ______.
