The following distribution shows the daily pocket allowance of children of a locality. The mean pocket allowance is ₹ 18. Find the missing frequency k.
Daily pocket allowance (in ₹) 11–13 13–15 15–17 17–19 19–21 21–23 23–25
Number of children 3 6 9 13 k 5 4
(class 10 CBSE SAMPLE PAPER 2017-18 MATHS)
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In this question we find the mean by direct method.
In this method find the class marks of class interval. These class marks would serve as the representative of whole class and are represented by xi. For each class interval we have the frequency fi corresponding to the class mark xi.
Class marks=( lower limit + upper limit)/2
Then find the product of fi, & xi for each class interval. Find Σ fi & Σfixi.
Use the formula :
Mean = Σfixi/ Σfi
[SOLUTION IS IN THE ATTACHMENT]
In this method find the class marks of class interval. These class marks would serve as the representative of whole class and are represented by xi. For each class interval we have the frequency fi corresponding to the class mark xi.
Class marks=( lower limit + upper limit)/2
Then find the product of fi, & xi for each class interval. Find Σ fi & Σfixi.
Use the formula :
Mean = Σfixi/ Σfi
[SOLUTION IS IN THE ATTACHMENT]
Attachments:
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2
Sigma fixi = 752 + 20f .
I hope it is helpful and this answer is correct by direct method.
So please mark me as a brainlist .
This question is from gala model paper 2022 class 10th. It is little bit different to the above asked question.
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