Advertisements
Advertisements
प्रश्न
The mean of the following distribution is 18. Find the frequency f of class 19 – 21.
| Class | 11-13 | 13-15 | 15-17 | 17-19 | 19-21 | 21-23 | 23-25 |
| Frequency | 3 | 6 | 9 | 13 | f | 5 | 4 |
उत्तर
| Class | Frequency fi | Mid value xi | `f_ix_i` |
| 11-13 | 3 | 12 | 36 |
| 13-15 | 6 | 14 | 84 |
| 15-17 | 9 | 16 | 144 |
| 17-19 | 13 | 18 | 234 |
| 19-21 | f | 20 | 20f |
| 21-23 | 5 | 22 | 110 |
| 23-25 | 4 | 24 | 96 |
Mean = `(sumf_ix_i)/(sum f_i) = (704 + 20f)/(40 + f) = 18 `
`=> 704 + 20f = 720 + 18f`
`=> 2f = 16`
`=> f = 8`
APPEARS IN
संबंधित प्रश्न
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.
Five coins were simultaneously tossed 1000 times and at each toss the number of heads were observed. The number of tosses during which 0, 1, 2, 3, 4 and 5 heads were obtained are shown in the table below. Find the mean number of heads per toss.
| No. of heads per toss | No. of tosses |
| 0 | 38 |
| 1 | 144 |
| 2 | 342 |
| 3 | 287 |
| 4 | 164 |
| 5 | 25 |
| Total | 1000 |
The mean of following frequency distribution is 54. Find the value of p.
| Class | 0-20 | 20-40 | 40-60 | 60-80 | 80-100 |
| Frequency | 7 | p | 10 | 9 | 13 |
Find the arithmetic mean of the following frequency distribution using step-deviation method:
| Age (in years) | 18 – 24 | 24 – 30 | 30 – 36 | 36 – 42 | 42 – 48 | 48 – 54 |
| Number of workers | 6 | 8 | 12 | 8 | 4 | 2 |
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 =
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 following table shows the weight of 12 students:
| Weight in kg. | 67 | 70 | 72 | 73 | 75 |
| Number of students | 4 | 3 | 2 | 2 | 1 |
Find the Mean weight.
The median from the table is?
| Value | Frequency |
| 7 | 2 |
| 8 | 1 |
| 9 | 4 |
| 10 | 5 |
| 11 | 6 |
| 12 | 1 |
| 13 | 3 |
Consider the following distribution of SO2 concentration in the air (in ppm = parts per million) in 30 localities. Find the mean SO2 concentration using assumed mean method. Also find the values of A, B and C.
| Class interval | Frequency (fi) | Class mark (xi) | di = xi - a |
| 0.00 - 0.04 | 4 | 0.02 | -0.08 |
| 0.04 - 0.08 | 9 | 0.06 | A |
| 0.08 - 0.12 | 9 | 0.10 | B |
| 0.12 - 0.16 | 2 | 0.14 | 0.04 |
| 0.16 - 0.20 | 4 | 0.18 | C |
| 0.20 - 0.24 | 2 | 0.22 | 0.12 |
| Total | `sumf_i=30` |
