Advertisements
Advertisements
Question
In calculating the mean of grouped data, grouped in classes of equal width, we may use the formula `barx = a + (sumf_i d_i)/(sumf_i)` where a is the assumed mean. a must be one of the mid-points of the classes. Is the last statement correct? Justify your answer.
Solution
No, it is not necessary that assumed mean consider as the mid-point of the class interval. It is considered as any value which is easy to simplify it.
APPEARS IN
RELATED QUESTIONS
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 |
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.
If the mean of the following data is 18.75. Find the value of p.
| x | 10 | 15 | P | 25 | 30 |
| f | 5 | 10 | 7 | 8 | 2 |
Find the mean of the following distribution:
| x | 10 | 30 | 50 | 70 | 89 |
| f | 7 | 8 | 10 | 15 | 10 |
The following table gives the wages of worker in a factory:
| Wages in ₹ | 45 - 50 | 50 - 55 | 55 - 60 | 60 - 65 | 65 - 70 | 70 - 75 | 75 - 80 |
| No. of Worker's | 5 | 8 | 30 | 25 | 14 | 12 | 6 |
Calculate the mean by the short cut method.
di is the deviation of xi from assumed mean a. If mean = `x+(sumf_id_i)/(sumf_i),` then x is ______.
In the formula `barx = a + (f_i d_i)/f_i`, for finding the mean of grouped data di’s are deviations from a of ______.
An aircraft has 120 passenger seats. The number of seats occupied during 100 flights is given in the following table:
| Number of seats | 100 – 104 | 104 – 108 | 108 – 112 | 112 – 116 | 116 – 120 |
| Frequency | 15 | 20 | 32 | 18 | 15 |
The mileage (km per litre) of 50 cars of the same model was tested by a manufacturer and details are tabulated as given below:
| Mileage (km/l) | 10 – 12 | 12 – 14 | 14 – 16 | 16 – 18 |
| Number of cars | 7 | 12 | 18 | 13 |
Find the mean mileage. The manufacturer claimed that the mileage of the model was 16 km/litre. Do you agree with this claim?
Which of the following cannot be determined graphically for a grouped frequency distribution?
