If a is taken as assumed mean for a data and denotes the deviation of from a, then arithmetic mean is given by
Here a = assumed mean
= frequency of class
= deviation of class
Illustration: Calculate the mean of the data given below.
Range of wages (in Rs) | 235-245 | 245-255 | 255-265 | 265-275 | 275-285 | 285-295 | 295-305 |
Numbers of workers | 15 | 25 | 32 | 47 | 15 | 12 | 4 |
Solution. To calculate the mean using assumed mean method, we will first find the class mark for each class and will then assume a value as the mean.
Range of wages |
wages |
Frequency
|
Deviation |
|
235-245 245-255 255-265 265-275 275-285 285-295 295-305 |
240 250 260 270=a 280 290 300 |
15 25 32 47 15 12 4 |
-30 -20 -10 0 10 20 30 |
-450 -500 -320 0 150 240 120 |
Total | 150 |
-760 |
By the assumed-mean method
The algebraic sum of the deviations from the mean is always ______________________. | |||
Right Option : A | |||
View Explanation |
In the method to calculate mean using assumed mean method, The value of assumed mean for the following data is_______________ .
| |||||||||||||||
Right Option : B | |||||||||||||||
View Explanation |
In the below given formula, which is used for finding the mean of grouped data, d s are the deviations from a of | |||
Right Option : C | |||
View Explanation |
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