The average of nine consecutive numbers is n . If the next two numbers are…

2022

The average of nine consecutive numbers is n . If the next two numbers are also included, the new average is:

  1. A.

    remain the same

  2. B.

    increase by 1

  3. C.

    increase by 1.5

  4. D.

    increase by 2

Attempted by 129 students.

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Correct answer: B

Let the nine consecutive numbers be x, x+1, x+2, ..., x+8. Their sum is:

Sum = x + (x+1) + (x+2) + ... + (x+8) = 9x + (1+2+...+8) = 9x + 36.

Average of these nine numbers = (9x + 36)/9 = x + 4. Given that this average is n, so n = x + 4.

The next two numbers are x+9 and x+10. Their sum is:

Sum = (x+9) + (x+10) = 2x + 19.

New total sum = (9x + 36) + (2x + 19) = 11x + 55.

New average = (11x + 55)/11 = x + 5.

Since n = x + 4, the new average = (x + 4) + 1 = n + 1.

Therefore, the new average increases by 1.

हिन्दी उत्तर:

मान लीजिए कि नौ क्रमिक संख्याएँ x, x+1, x+2, ..., x+8 हैं। उनका योग है:

योग = x + (x+1) + (x+2) + ... + (x+8) = 9x + (1+2+...+8) = 9x + 36।

इन नौ संख्याओं का औसत = (9x + 36)/9 = x + 4। दिया गया है कि यह औसत n है, इसलिए n = x + 4।

अगली दो संख्याएँ x+9 और x+10 हैं। उनका योग है:

योग = (x+9) + (x+10) = 2x + 19।

नया कुल योग = (9x + 36) + (2x + 19) = 11x + 55।

नया औसत = (11x + 55)/11 = x + 5।

चूँकि n = x + 4, नया औसत = (x + 4) + 1 = n + 1।

इसलिए, नया औसत 1 बढ़ता है।

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