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प्रश्न
Find the following table gives the distribution of the life time of 400 neon lamps:
| Life time (in hours) | Number of lamps |
| 1500 – 2000 | 14 |
| 2000 – 2500 | 56 |
| 2500 – 3000 | 60 |
| 3000 – 3500 | 86 |
| 3500 – 4000 | 74 |
| 4000 – 4500 | 62 |
| 4500 – 5000 | 48 |
Find the median life time of a lamp.
उत्तर
The cumulative frequencies with their respective class intervals are as follows.
| Life time | Number of lamps (fi) |
Cumulative frequency |
| 1500 − 2000 | 14 | 14 |
| 2000 − 2500 | 56 | 14 + 56 = 70 |
| 3000 − 3500 | 60 | 70 + 60 = 130 |
| 3000 − 3500 | 86 | 130 + 86 = 216 |
| 3500 − 4000 | 74 | 216 + 74 = 290 |
| 4000 − 4500 | 62 | 290 + 62 = 352 |
| 4500 − 5000 | 48 | 352 + 48 = 400 |
| Total (n) | 400 |
It can be observed that the cumulative frequency just greater than `n/2 (i.e 400/2 = 200)` is 216
belonging to class interval 3000 − 3500.
Median class = 3000 − 3500
Lower limit (l) of median class = 3000
Frequency (f) of median class = 86
Cumulative frequency (cf) of class preceding median class = 130
Class size (h) = 500
Median = `l +((n/2 -cf)/f)xxh`
= `3000+ ((200-130)/86)xx500`
= `3000+(70xx500)/86`
= 3406.976
Therefore, the median life time of lamps is 3406.98 hours.
संबंधित प्रश्न
For a certain frequency distribution, the values of Assumed mean (A) = 1300, `sumf_id_i` = 900 and `sumfi` = 100. Find the value of mean (`barx`) .
The following is the distribution of the size of certain farms from a taluka (tehasil):
| Size of Farms (in acres) |
Number of Farms |
| 5 – 15 | 7 |
| 15 – 25 | 12 |
| 25 – 35 | 17 |
| 35 – 45 | 25 |
| 45 – 55 | 31 |
| 55 – 65 | 5 |
| 65 – 75 | 3 |
Find median size of farms.
The marks obtained by 30 students in a class assignment of 5 marks are given below.
| Marks | 0 | 1 | 2 | 3 | 4 | 5 |
| No. of Students |
1 | 3 | 6 | 10 | 5 | 5 |
Calculate the mean, median and mode of the above distribution
A survey regarding the height (in cm) of 51 girls of class X of a school was conducted and the following data was obtained:
| Height in cm | Number of Girls |
| Less than 140 | 4 |
| Less than 145 | 11 |
| Less than 150 | 29 |
| Less than 155 | 40 |
| Less than 160 | 46 |
| Less than 165 | 51 |
Find the median height.
Given below is the number of units of electricity consumed in a week in a certain locality:
| Class | 65 – 85 | 85 – 105 | 105 – 125 | 125 – 145 | 145 – 165 | 165 – 185 | 185 – 200 |
| Frequency | 4 | 5 | 13 | 20 | 14 | 7 | 4 |
Calculate the median.
The median of the following data is 16. Find the missing frequencies a and b if the total of frequencies is 70.
| Class | 0 – 5 | 5 – 10 | 10 – 15 | 15 – 20 | 20 – 25 | 25 – 30 | 30 – 35 | 35 – 40 |
| Frequency | 12 | a | 12 | 15 | b | 6 | 6 | 4 |
In the following data the median of the runs scored by 60 top batsmen of the world in one-day international cricket matches is 5000. Find the missing frequencies x and y.
| Runs scored | 2500 – 3500 | 3500 – 4500 | 4500 – 5500 | 5500 – 6500 | 6500 – 7500 | 7500 - 8500 |
| Number of batsman | 5 | x | y | 12 | 6 | 2 |
If the median of the following frequency distribution is 32.5, find the values of `f_1 and f_2`.
| Class | 0 – 10 | 10 – 20 | 20 – 30 | 30 -40 | 40 – 50 | 50 – 60 | 60 – 70 | Total |
| Frequency | `f_1` |
5 |
9 | 12 | `f_2` | 3 | 2 | 40 |
Find the median from the following data:
| Marks | No of students |
| Below 10 | 12 |
| Below 20 | 32 |
| Below 30 | 57 |
| Below 40 | 80 |
| Below 50 | 92 |
| Below 60 | 116 |
| Below 70 | 164 |
| Below 80 | 200 |
Grouped frequency distribution of supply of milk to hotels and the number of hotels is given in the following table. Find the mode of the supply of milk.
| Milk (Litre) | 1 - 3 | 3 - 5 | 5 - 7 | 7 - 9 | 9 - 11 | 11 - 13 |
| No. of hotels | 7 | 5 | 15 | 20 | 35 | 18 |
In the graphical representation of a frequency distribution, if the distance between mode and mean is ktimes the distance between median and mean, then write the value of k.
The arithmetic mean and mode of a data are 24 and 12 respectively, then its median is
In the following table, Σf = 200 and mean = 73. Find the missing frequencies f1, and f2.
| x | 0 | 50 | 100 | 150 | 200 | 250 |
| f | 46 | f1 | f2 | 25 | 10 | 5 |
Find the median of:
66, 98, 54, 92, 87, 63, 72.
Consider the following frequency distribution:
| Class | 0 – 5 | 6 – 11 | 12 – 17 | 18 – 23 | 24 – 29 |
| Frequency | 13 | 10 | 15 | 8 | 11 |
The upper limit of the median class is:
Consider the data:
| Class | 65 – 85 | 85 – 105 | 105 – 125 | 125 – 145 | 145 – 165 | 165 – 185 | 185 – 205 |
| Frequency | 4 | 5 | 13 | 20 | 14 | 7 | 4 |
The difference of the upper limit of the median class and the lower limit of the modal class is:
The median of an ungrouped data and the median calculated when the same data is grouped are always the same. Do you think that this is a correct statement? Give reason.
Calculate the median of marks of students for the following distribution:
| Marks | Number of students |
| More than or equal to 0 | 100 |
| More than or equal to 10 | 93 |
| More than or equal to 20 | 88 |
| More than or equal to 30 | 70 |
| More than or equal to 40 | 59 |
| More than or equal to 50 | 42 |
| More than or equal to 60 | 34 |
| More than or equal to 70 | 20 |
| More than or equal to 80 | 11 |
| More than or equal to 90 | 4 |
Heights of 50 students of class X of a school are recorded and following data is obtained:
| Height (in cm) | 130 – 135 | 135 – 140 | 140 – 145 | 145 – 150 | 150 – 155 | 155 – 160 |
| Number of students | 4 | 11 | 12 | 7 | 10 | 6 |
Find the median height of the students.
Read the following passage and answer the questions given below.
|
Electric buses are becoming popular nowadays. These buses have the electricity stored in a battery. Electric buses have a range of approximately 280 km with just charge. These buses are superior to diesel buses as they reduce brake wear and also reduce pollution. 'transport department of a city wants to buy some electric buses for the city. So, the department wants to know the distance travelled by existing public transport buses in a day. The following data shows the distance travelled by 50 existing public transport buses in a day.
|
| Daily distance travelled (in km) | 100 – 120 | 120 – 140 | 140 – 160 | 160 – 180 | 180 – 200 |
| Number of buses | 12 | 14 | 8 | 6 | 10 |
- Find the 'median' distance travelled by a bus.
- Find the 'mean (average)' distance travelled by a bus.
