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The mean of three numbers is 10. The mean of other four numbers is 12. Find the mean of all the numbers. - Mathematics

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Question

The mean of three numbers is 10. The mean of other four numbers is 12. Find the mean of all the numbers.

Sum
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Solution

Mean of three numbers = `"Sum of three numbers"/3`

⇒ `10 = "Sum of three numbers"/3`  ...[∵ Mean of three numbers = 10, given]

Here, sum of three numbers = 30

Mean of other four numbers = `"Sum of other four numbers"/4`

⇒ `12 = "Sum of other four numbers"/4`  ...`[(∵ "Mean of other four"),("numbers" = 12","  "given")]`

Hence, sum of other four numbers = 48

∴ Mean of all the numbers = `"Sum of all the numbers"/"Total numbers"`

= `(["Sum of first three numbers" + "Sum of other four numbers"])/7`

= `(30 + 48)/7`

= `78/7`

= 11.14

Hence, mean of all the numbers is 11.14.

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Chapter 3: Data Handling - Exercise [Page 78]

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NCERT Exemplar Mathematics [English] Class 7
Chapter 3 Data Handling
Exercise | Q 67. | Page 78

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