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प्रश्न
Find the mean (correct to one place of decimal) by using short-cut method.
|
x |
40 |
41 |
43 |
45 |
46 |
49 |
50 |
|
f |
14 |
28 |
38 |
50 |
40 |
20 |
10 |
उत्तर
Let the assumed mean A = 45
| x | f | d = x – a = x – 45 | fd |
| 40 | 14 | –5 | –70 |
| 41 | 28 | –4 | –112 |
| 43 | 38 | –2 | –76 |
| A = 45 | 50 | 0 | 0 |
| 46 | 40 | 1 | 40 |
| 49 | 20 | 4 | 80 |
| 50 | 10 | 5 | 50 |
| Σf = 200 | Σfd = –88 |
∴ Mean = `A + (Σfd)/(Σf)`
= `45 + ((-88))/200`
= `45 - 11/25`
= `(1125 - 11)/25`
= `1114/25`
= 44.6
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संबंधित प्रश्न
Calculate the mean of the distribution given below using the shortcut method.
| Marks | 11-20 | 21-30 | 31-40 | 41-50 | 51-60 | 61-70 | 71-80 |
| No. of students | 2 | 6 | 10 | 12 | 9 | 7 | 4 |
The following are the marks obtained by 70 boys in a class test:
| Marks | No. of boys |
| 30 – 40 | 10 |
| 40 – 50 | 12 |
| 50 – 60 | 14 |
| 60 – 70 | 12 |
| 70 – 80 | 9 |
| 80 – 90 | 7 |
| 90 – 100 | 6 |
Calculate the mean by:
Short-cut method
Draw a histogram for the following distribution and estimate the mode:
| I.Q. Score | 80-100 | 100-120 | 120-140 | 140-160 | 160-180 | 180-200 |
| No. of Students | 6 | 9 | 16 | 13 | 4 | 2 |
Find the mean of 53, 61, 60, 67 and 64.
Find the mean of the first six multiples of 5.
The rainfall (in mm) in a city on 7 days of a certain week is recorded as follows:
| Day: | Mon | Tue | Wed | Thus | Fri | Sat | Sun |
| Rainfall (in mm): | 0.5 | 2.7 | 2.6 | 0.5 | 2 | 5.8 | 1.5 |
Find the total and average (mean) rainfall for the week.
The mean of marks scored by 100 students was found to be 40, later on, it was discovered that a score of 53 was misread as 83. Find the correct mean.
Find the median of the given data: 35, 25, 34, 36, 45, 18, 28
Given below are heights of 15 boys of a class measured in cm:
128, 144, 146, 143, 136, 142, 138, 129, 140, 152, 144, 140, 150, 142, 154
Find the median height of the boys.
The marks of 200 students in a test were recorded as follows:
| Marks % |
0-10 | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 | 60-70 | 70-80 | 80-90 | 90-100 |
| No. of students |
5 | 7 | 11 | 20 | 40 | 52 | 36 | 15 | 9 | 5 |
Using graph sheet draw ogive for the given data and use it to find the,
- median,
- number of students who obtained more than 65% marks
- number of students who did not pass, if the pass percentage was 35.
