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Harshita Jain posted an Question
October 13, 2020 • 04:38 am
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30 points
30 points
- UGC NET
- Commerce
The average of 12 numbers is 9. if each number is multiplied by 2 and added to 3, the average of the new set of numbers is b) 18 (a) 9 (d) 27 (c) 21
The average of 12 numbers is 9. If each number is multiplied by 2 and added to 3, the average of the new set of numbers is B) 18 (A) 9 (D) 27 (C) 21
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Rishab Soni
Its 21. The average of 12 numbers is 9. That means the total number is 12 X 9 = 108 if each number is multiplied by 2, the average will also be multiplied by 2. That is the new average will be 9X2 = 18. And then 3 is added to each number. So average will also be added by 3 That will give you 18+3 = 21. You can do this another way too. Total number is 12X9 = 108 Each number is multiplied by 2 that means new average is 9X2 = 18 New total number will be 12X18 = 216 3 is added to each number that means total increment to the total number is 12X3 = 36 New total number will be 216 + 36 = 252 And thus, new average will be 252/12 = 21 Hope that helps you.
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in book this is mentioned 🤔 that is why i had doubt
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Book one has a single mistake. It has added 3 in just one place. Question has mentioned that 3 is added to each number. That means total addition should be 36. If you add that correction, you'll get 21. (108X2+36)/12 = 21.
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nice explanation Rishab sir
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Rucha rajesh shingvekar
Correct Option: C If each number of a set be multiplied by m, the average gets multiplied by m. If each number of a set be increased by p, the average gets increased by p. Here , The average of 12 numbers = 9 m = 2 , p = 3 ∴ Required average = m × The average of 12 numbers + p = 2 × 9 + 3 = 21
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Rucha rajesh shingvekar
Let the sum of 12 no. be x=x1+x2+........x12 average=total no.sum of no. ⇒9=12x sum=108 let sum of new numbers is according to question (x1×2+3)+(x2×2+3)+......(x12×2+3) ⇒2×(x1+x2+.....x12)+12×3 sum=2×108+12×3=216+36=252 average=252/12=21 ∴correct option is C.
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in book this is mentioned 🤔 that is why i had doubt
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Priya gulani![best-answer]()
option c 21