Advertisements
Advertisements
प्रश्न
If the mean of the following frequency distribution is 24, find the value of p.
| Class | 0-10 | 10-20 | 20-30 | 30-40 | 40-50 |
| Frequency | 3 | 4 | p | 3 | 2 |
उत्तर
The given data is shown as follows:
| Class | Frequency`(f_i)` | Mid values`(x_i)` | `(f_i x_i)` |
| 0-10 | 3 | 5 | 15 |
| 10-20 | 4 | 15 | 60 |
| 20-30 | p | 25 | 25p |
| 30-40 | 3 | 35 | 105 |
| 40-50 | 2 | 45 | 90 |
| Total | `sum f_i = 12 +p` |
`sum f_i x_i = 270 +25p` |
The mean of the given data is given by,
x =`(sum_(i) f_i x_i)/(sum_(i) f_i )`
⇒24 = `(270+25p)/(12+p)`
⇒24 (12+p) = 270 + 25p
⇒ 288 + 24p = 270 + 25p
⇒ 25p - 24p = 288 -270
⇒p = 18
Hence, the value of p is 18.
APPEARS IN
संबंधित प्रश्न
A class teacher has the following absentee record of 40 students of a class for the whole term. Find the mean number of days a student was absent.
| Number of days | 0 - 6 | 6 - 10 | 10 -14 | 14 -20 | 20 -28 | 28 -38 | 38 -40 |
| Number of students | 11 | 10 | 7 | 4 | 4 | 3 | 1 |
The following table gives the number of children of 150 families in a village. Find the average number of children per family.
| No. of children (x) | 0 | 1 | 2 | 3 | 4 | 5 |
| No. of families (f) | 10 | 21 | 55 | 42 | 15 | 7 |
Find the mean from the following frequency distribution of marks at a test in statistics:
| Marks(x) | 5 | 10 | 15 | 20 | 25 | 30 | 35 | 40 | 45 | 50 |
| No. of students (f) | 15 | 50 | 80 | 76 | 72 | 45 | 39 | 9 | 8 | 6 |
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 |
Find the mean of each of the following frequency distributions
| Class interval | 0 - 8 | 8 - 16 | 16 - 24 | 24 - 32 | 32 - 40 |
| Frequency | 5 | 6 | 4 | 3 | 2 |
The following table gives the literacy rate (in percentage) in 40 cities. Find the mean literacy rate, choosing a suitable method .
| Literacy rate(%) |
45 – 55 | 55 – 65 | 65 – 75 | 75 – 85 | 85 – 95 |
| Number of cities |
4 | 11 | 12 | 9 | 4 |
The arithmetic mean of 1, 2, 3, ... , n is
While computing mean of grouped data, we assume that the frequencies are ______.
The measurements (in mm) of the diameters of the head of the screws are given below :
| Diameter (in mm) | no. of screws |
| 33 - 35 | 9 |
| 36 - 38 | 21 |
| 39 - 41 | 30 |
| 42 - 44 | 22 |
| 45 - 47 | 18 |
Calculate the mean diameter of the head of a screw by the ' Assumed Mean Method'.
The Mean of n observation x1, x2,..., xn is `bar"X"`. If (a - b) is added to each of the observation, show that the mean of the new set of observation is `bar"X"` + (a - b).
