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The mean marks of 8 girls in a class test is 52 and the mean marks of 12 boys of the same class in the same test is 51. Find the mean marks of all the 20 students in the class. - Mathematics

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Question

The mean marks of 8 girls in a class test is 52 and the mean marks of 12 boys of the same class in the same test is 51. Find the mean marks of all the 20 students in the class.

Sum
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Solution

The mean marks of the 8 girls is 52

Total marks of girls = mean × number of girls

= 52 × 8

= 416

The mean marks of the 12 boys is 51

Total marks of boys = mean × number of boys

= 51 × 12

= 612

Total marks of all students = 416 + 612

= 1028

Mean marks of all students = `"Total marks of all students​"/"Number of Students"`

= `1028/20`

= 51.4

∴ The mean marks of all the 20 students in the class is 51.4.

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Chapter 15: Statistics - EXERCISE 15B [Page 189]

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B Nirmala Shastry Mathematics [English] Class 9 ICSE
Chapter 15 Statistics
EXERCISE 15B | Q 14. | Page 189
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