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प्रश्न
While computing mean of grouped data, we assume that the frequencies are ______.
विकल्प
evenly distributed over all the classes
centred at the class marks of the classes
centred at the upper limit of the classes
centred at the lower limit of the classes
उत्तर
While computing mean of grouped data , we assume that the frequencies are centred at the class marks of the classes.
Explanation:-
We know that while computing the mean of a grouped data, the frequencies are centered at the class marks of the classes.
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संबंधित प्रश्न
The following table gives the distribution of total household expenditure (in rupees) of manual workers in a city. Find the average expenditure (in rupees) per household.
| Expenditure (in rupees) (x1) |
Frequency(f1) |
| 100 - 150 | 24 |
| 150 - 200 | 40 |
| 200 - 250 | 33 |
| 250 - 300 | 28 |
| 300 - 350 | 30 |
| 350 - 400 | 22 |
| 400 - 450 | 16 |
| 450 - 500 | 7 |
Find the mean of each of the following frequency distributions
| Class interval | 50 - 70 | 70 - 90 | 90 - 110 | 110 - 130 | 130 - 150 | 150 - 170 |
| Frequency | 18 | 12 | 13 | 27 | 8 | 22 |
During a medical check-up, the number of heartbeats per minute of 30 patients were recorded and summarized as follows:
| Number of heartbeats per minute |
65 – 68 | 68 – 71 | 71 – 74 | 74 – 77 | 77 – 80 | 80 – 83 | 83 - 86 |
| Number of patients |
2 | 4 | 3 | 8 | 7 | 4 | 2 |
Find the mean heartbeats per minute for these patients, choosing a suitable method.
Weight of 60 eggs were recorded as given below:
| Weight (in grams) | 75 – 79 | 80 – 84 | 85 – 89 | 90 – 94 | 95 – 99 | 100 - 104 | 105 - 109 |
| No. of eggs | 4 | 9 | 13 | 17 | 12 | 3 | 2 |
Calculate their mean weight to the nearest gram.
The following table shows the income of farmers in a grape season. Find the mean of their income.
|
Income
(Thousand Rupees)
|
20 - 30 | 30 - 40 | 40 - 50 | 50 - 60 | 60 - 70 | 70 - 80 |
| Farmers | 10 | 11 | 15 | 16 | 18 | 14 |
If the mean of observation \[x_1 , x_2 , . . . . , x_n is x\] then the mean of x1 + a, x2 + a, ....., xn + a is
The contents of 100 match box were checked to determine the number of match sticks they contained.
| Number of match sticks | Number of boxes |
| 35 | 6 |
| 36 | 10 |
| 37 | 18 |
| 38 | 25 |
| 39 | 21 |
| 40 | 12 |
| 41 | 8 |
(i) Calculate correct to one decimal place, the mean number of match sticks per box.
(ii) Determine how many matchsticks would have to be added. To the total contents of the 100 boxes to bring the mean up exactly 39 match sticks.
Find the mean wage of a worker from the following data:
| Wages (In ₹) | 1400 | 1450 | 1500 | 1550 | 1600 | 1650 | 1700 |
| Number of workers | 15 | 20 | 18 | 27 | 15 | 3 | 2 |
If mean = (3median - mode) . k, then the value of k is ______.
There is a grouped data distribution for which mean is to be found by step deviation method.
| Class interval | Number of Frequency (fi) | Class mark (xi) | di = xi - a | `u_i=d_i/h` |
| 0 - 100 | 40 | 50 | -200 | D |
| 100 - 200 | 39 | 150 | B | E |
| 200 - 300 | 34 | 250 | 0 | 0 |
| 300 - 400 | 30 | 350 | 100 | 1 |
| 400 - 500 | 45 | 450 | C | F |
| Total | `A=sumf_i=....` |
Find the value of A, B, C, D, E and F respectively.
