Advertisements
Advertisements
प्रश्न
Candidates of four schools appear in a mathematics test. The data were as follows:-
| Schools | No. of Candidates | Average Score |
| I | 60 | 75 |
| II | 48 | 80 |
| III | NA | 55 |
| IV | 40 | 50 |
If the average score of the candidates of all the four schools is 66, find the number of candidates that appeared from school III.
उत्तर
Let the number of candidates from school III = P
| Schools |
No. of Candidates (N1) |
Average scores (x1) |
| I | 60 | 75 |
| II | 48 | 80 |
| III | P | 55 |
| IV | 40 | 50 |
Given
Average score or all schools = 66
`rArr(N_1barx_1+N_2barx_2+N_3barx_3+N_4barx_4)/(N_1+N_2+N_3+N_4)=66`
`rArr(60xx75+48xx80+Pxx55+40xx50)/(60+48+P+40)=66`
`rArr(4500+3840+55P+2000)/(148+P)=66`
⇒ 4500 + 3840 + 55P + 2000 = 66(148 + P)
⇒ 10340 + 55P = 66P + 9768
⇒ 10340 - 9768 = 66P - 55P
⇒ 572 = 11P
`rArrP=572/11`
⇒ P = 52
APPEARS IN
संबंधित प्रश्न
The following table gives the literacy rate (in percentage) of 35 cities. Find the mean literacy rate.
| Literacy rate (in %) | 45 − 55 | 55 − 65 | 65 − 75 | 75 − 85 | 85 − 95 |
| Number of cities | 3 | 10 | 11 | 8 | 3 |
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 |
The following table shows the marks scored by 140 students in an examination of a certain paper:
| Marks: | 0 - 10 | 10 - 20 | 20 - 30 | 30 - 40 | 40 - 50 |
| Number of students: | 20 | 24 | 40 | 36 | 20 |
Calculate the average marks by using all the three methods: direct method, assumed mean deviation and shortcut method.
The mean of the following frequency distribution is 62.8 and the sum of all the frequencies is 50. Compute the missing frequency f1 and f2.
| Class | 0 - 20 | 20 - 40 | 40 - 60 | 60 - 80 | 80 - 100 | 100 - 120 |
| Frequency | 5 | f1 | 10 | f2 | 7 | 8 |
The following distribution shows the daily pocket allowance given to the children of a multistorey building. The average pocket allowance is Rs 18.00. Find out the missing frequency.
| Class interval | 11 - 13 | 13 - 15 | 15 - 17 | 17 - 19 | 19 - 21 | 21 - 23 | 23 - 25 |
| Frequency | 7 | 6 | 9 | 13 | - | 5 | 4 |
The following table shows the marks scored by 80 students in an examination:
| Marks | 0 – 5 | 5 – 10 | 10 – 15 | 15 – 20 | 20 – 25 | 25 – 30 | 30 – 35 | 35 – 40 |
| No. of students |
3 | 10 | 25 | 49 | 65 | 73 | 78 | 80 |
Find the mean of the following frequency distribution:
| Class Interval | Frequency |
| 0 - 50 | 4 |
| 50 - 100 | 8 |
| 100 - 150 | 16 |
| 150 - 200 | 13 |
| 200 - 250 | 6 |
| 250 - 300 | 3 |
The average score of girls in class X examination in school is 67 and that of boys is 63. The average score for the whole class is 64.5. Find the percentage of girls and boys in the class.
Mean of 100 items is 49. It was discovered that three items which should have been 60, 70, 80 were wrongly read as 40, 20, 50 respectively. The correct mean is ______.
An analysis of particular information is given in the following table.
| Age Group | 0 – 10 | 10 – 20 | 20 – 30 | 30 – 40 | 40 – 50 |
| Frequency | 2 | 5 | 6 | 5 | 2 |
For this data, mode = median = 25. Calculate the mean. Observing the given frequency distribution and values of the central tendency interpret your observation.
