मराठी

The mean marks of 20 students is 62. It was later discovered that one of the students marks were written wrongly as 86 instead of 68. Find the correct mean. - Mathematics

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प्रश्न

The mean marks of 20 students is 62. It was later discovered that one of the students marks were written wrongly as 86 instead of 68. Find the correct mean.

बेरीज
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उत्तर

The mean marks of 20 students is 62

Total marks of all students (incorrect) = mean × number of students

= 62 × 20

= 1240

The incorrect mark for one student was 86, but the correct mark is 68. The difference between the incorrect and correct marks is

86 − 68 = 18

Correct total marks = 1240 − 18

= 1222

Correct mean = `"Correct total marks"/"Number of students"`

= `(1222)/20`

= 61.1

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पाठ 15: Statistics - EXERCISE 15B [पृष्ठ १८९]

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बी निर्मला शास्त्री Mathematics [English] Class 9 ICSE
पाठ 15 Statistics
EXERCISE 15B | Q 11. | पृष्ठ १८९
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