 # RS Aggarwal Solutions Class 9 Mathematics Solutions for Mean Median And Mode Of Ungrouped Data Exercise 18A in Chapter 18 - Mean Median And Mode Of Ungrouped Data

Question 24 Mean Median And Mode Of Ungrouped Data Exercise 18A

The mean score of 25 observations is 80 and the mean score of another 55 observations is 60. Determine

the mean score of the whole set of observations.

It is given that

Mean score of 25 observations = 80

So the total score = 25 (80) = 2000

Mean score of 55 observations = 60

So the total score = 55 (60) = 3300

We know that

Total number of observations = 25 + 55 = 80

So the total score = 2000 + 3300 = 5300

Mean score = total score/total number of observations

By substituting the values

Mean score = 5300/80

So we get

Mean score = 66.25

Therefore, the mean score of the whole set of observations is 66.25.

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