Question
Download Solution PDFA student solves n question of mathematics. The average of unit digits of eight answers is 7. The average of unit digits of the remaining answers is 2. If the average of unit digits of all the answers is 4, then what is the value of n?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFGiven:
A student solves 'n' question of mathematics.
The average of unit digits of eight answers = 7
The average of unit digits of the remaining answers = 2
If the average of unit digits of all the answers = 4
Calculation:
According to the question,
The average of unit digits of eight answers = 7
The sum of unit digits of eight answers = 7 × 8 = 56
The average of unit digits of the (n - 8) answers = 2
The sum of unit digits of the (n - 8) answers = (n - 8) × 2 = 2n - 16
The average of unit digits of all the answers = 4
The sum of unit digits of all the answers = 4n
Now,
⇒ 4n = 2n - 16 + 56
⇒ 2n = 40
⇒ n = 20
Therefore, "20" is the required answer.
Last updated on May 12, 2025
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