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प्रश्न
If the mean of x, x + 2, x + 4, x + 6 and x + 8 is 13, find the value of x. Sum of data.
उत्तर
∵ Mean = `"Sum of data"/"Number of data"`
`=> 13 = (x + (x + 2) + (x + 4) + (x + 6) + (x + 8))/5`
`=> 13 = (5x + 20)/5`
`=> 13 xx 5 = 5x + 20`
⇒ 65 - 20 = 5x
⇒ 45 = 5x
⇒ x = `45/5`
∴ x = 9
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संबंधित प्रश्न
The following distribution represents the height of 160 students of a school.
| Height (in cm) | No. of Students |
| 140 – 145 | 12 |
| 145 – 150 | 20 |
| 150 – 155 | 30 |
| 155 – 160 | 38 |
| 160 – 165 | 24 |
| 165 – 170 | 16 |
| 170 – 175 | 12 |
| 175 – 180 | 8 |
Draw an ogive for the given distribution taking 2 cm = 5 cm of height on one axis and 2 cm = 20 students on the other axis. Using the graph, determine:
- The median height.
- The interquartile range.
- The number of students whose height is above 172 cm.
The mean of the following distribution is 52 and the frequency of class interval 30-40 is ‘f’. Find ‘f’.
| Class Interval | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 | 60-70 | 70-80 |
| Frequency | 5 | 3 | f | 7 | 2 | 6 | 13 |
Attempt this question on graph paper.
| Age (yrs ) | 5-15 | 15-25 | 25-35 | 35-45 | 45-55 | 55-65 | 65-75 |
| No.of casualties | 6 | 10 | 15 | 13 | 24 | 8 | 7 |
(1) Construct the 'less than' Cumulative frequency curve for the above data. using 2 cm =10 years on one axis and 2 cm =10 casualties on the other.
(2)From your graph determine :
(a)the median
(b)the lower quartile
The marks of 200 students in a test were recorded as follows:
| Marks | No. of students |
| 10-19 | 7 |
| 20-29 | 11 |
| 30-39 | 20 |
| 40-49 | 46 |
| 50-59 | 57 |
| 60-69 | 37 |
| 70-79 | 15 |
| 80-89 | 7 |
Construct the cumulative frequency table. Drew the ogive and use it too find:
(1) the median and
(2) the number of student who score more than 35% marks.
Draw a histogram and hence estimate the mode for the following frequency distribution:
| Class | 0-10 | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 |
| Freq | 2 | 8 | 10 | 5 | 4 | 3 |
Following 10 observations are arranged in ascending order as follows.
2, 3, 5, 9, x + 1, x + 3, 14, 16, 19, 20
If the median of the data is 11, find the value of x.
Find the median of the following:
11, 8, 15, 5, 9, 4, 19, 6, 18
The pocket expenses (per day) of Anuj, during a certain week, from Monday to Saturday were ₹85.40, ₹88.00, ₹86.50, ₹84.75, ₹82.60 and ₹87.25. Find the mean pocket expenses per day.
Find the mean and the median of: 10,12, 12, 15, 15, 17, 18, 18, 18 and 19
An incomplete frequency distribution is given below
| Variate | Frequency |
| 10 – 20 | 12 |
| 20 – 30 | 30 |
| 30 – 40 | ? |
| 40 – 50 | 65 |
| 50 – 60 | 45 |
| 60 – 70 | 25 |
| 70 – 80 | 18 |
| Total | 229 |
Median value is 46, the missing frequency is:
