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सी.आई.एस.सी.ई.आईसीएसई ICSE Class 7

The Mean of Marks Scored by 100 Students Was Found to Be 40, Later On, It Was Discovered that a Score of 53 Was Misread as 83. Find the Correct Mean.

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प्रश्न

The mean of marks scored by 100 students was found to be 40, later on, it was discovered that a score of 53 was misread as 83. Find the correct mean.

योग
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उत्तर

Total number of students = 100

Initial mean = 40

We first calculate the total sum of marks based on the initial mean:

Total Sum of Marks = Mean × Number of Students

Total Sum of Marks = 40 × 100 = 4000

A score of 53 was mistakenly read as 83.

The error introduced an extra 83 − 53 = 30 marks to the total.

To correct the total, subtract this error:

Correct Total Sum = Initial Total Sum − 30

Correct Total Sum = 4000 − 30 = 3970

The correct mean is calculated by dividing the corrected total sum by the number of students:

Correct Mean = `"Correct total Sum"/"Number of Students"`

Correct Mean = `3970/100`

= 39.7

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अध्याय 21: Data Handling - Exercise 21 (B)

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सेलिना Concise Mathematics [English] Class 7 ICSE
अध्याय 21 Data Handling
Exercise 21 (B) | Q 17
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