Advertisements
Advertisements
प्रश्न
Find the mean of each of the following frequency distributions
| Class interval | 0 - 8 | 8 - 16 | 16 - 24 | 24 - 32 | 32 - 40 |
| Frequency | 6 | 7 | 10 | 8 | 9 |
उत्तर
Let the assumed mean A = 20
| Class interval |
Mid-value(x1) | d1 = x1 - 20 | `"u"_1=(x_1-20)/8` | f1 | f1u1 |
| 0 - 8 | 4 | -16 | -2 | 6 | -12 |
| 8 - 16 | 12 | -8 | -1 | 7 | -7 |
| 16 - 24 | 20 | 0 | 0 | 10 | 0 |
| 24 - 32 | 28 | 8 | 1 | 8 | 8 |
| 32 - 40 | 36 | 16 | 2 | 9 | 18 |
| N = 40 | `sumf_1"u"_1=7` |
We have
A = 20 h = 8
Mean `=A+hxx(sumf_1"U"_1)/N`
`=20+8xx7/40`
`=20+56/40`
= 20 + 1.4
= 21.4
APPEARS IN
संबंधित प्रश्न
Thirty women were examined in a hospital by a doctor and the number of heartbeats per minute were recorded and summarized as follows. Fine the mean heartbeats per minute for these women, choosing a suitable method.
| Number of heartbeats per minute | 65 - 68 | 68 - 71 | 71 - 74 | 74 - 77 | 77 - 80 | 80 - 83 | 83 - 86 |
| Number of women | 2 | 4 | 3 | 8 | 7 | 4 | 2 |
To find out the concentration of SO2 in the air (in parts per million, i.e., ppm), the data was collected for 30 localities in a certain city and is presented below:
| concentration of SO2 (in ppm) | 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 |
Find the mean concentration of SO2 in the air.
Calculate the mean for the following distribution:-
| x | 5 | 6 | 7 | 8 | 9 |
| f | 4 | 8 | 14 | 11 | 3 |
The mean of the following frequency data is 42, Find the missing frequencies x and y if the sum of frequencies is 100
|
Class interval |
0-10 | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 | 60-70 | 70-80 |
| Frequency | 7 | 10 | x | 13 | y | 10 | 14 | 9 |
Find x and y.
In an annual examination, marks (out of 90) obtained by students of Class X in mathematics are given below:
| Marks Obtained |
0 – 15 | 15 – 30 | 30 – 45 | 45 – 60 | 60 – 75 | 75 – 90 |
| Number of students |
2 | 4 | 5 | 20 | 9 | 10 |
Find the mean marks.
The mean of n observation is `overlineX`. If the first observation is increased by 1, the second by 2, the third by 3, and so on, then the new mean is
If the arithmetic mean, 7, 8, x, 11, 14 is x, then x =
di is the deviation of xi from assumed mean a. If mean = `x+(sumf_id_i)/(sumf_i),` then x is ______.
An aircraft has 120 passenger seats. The number of seats occupied during 100 flights is given in the following table:
| Number of seats | 100 – 104 | 104 – 108 | 108 – 112 | 112 – 116 | 116 – 120 |
| Frequency | 15 | 20 | 32 | 18 | 15 |
Find the mean for the following distribution:
| Class Interval | 20 - 40 | 40 - 60 | 60 - 80 | 80 - 100 |
| Frequency | 4 | 7 | 6 | 3 |
