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The average of 5 numbers is 6.8. If one of the numbers is

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by BTGmoderatorDC » Wed Aug 21, 2019 5:34 pm

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The average of 5 numbers is 6.8. If one of the numbers is multiplied by a factor of 3, the average of the numbers increases to 9.2. What number is multiplied by 3?

(A) 1.5
(B) 3.0
(C) 3.9
(D) 4.0
(E) 6.0

OA E

Source: Veritas Prep
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Source: — Problem Solving |

by Jay@ManhattanReview » Wed Aug 21, 2019 8:39 pm
BTGmoderatorDC wrote:The average of 5 numbers is 6.8. If one of the numbers is multiplied by a factor of 3, the average of the numbers increases to 9.2. What number is multiplied by 3?

(A) 1.5
(B) 3.0
(C) 3.9
(D) 4.0
(E) 6.0

OA E

Source: Veritas Prep
Given that the average of 5 numbers is 6.8, the sum of the numbers = 5*6.8 = 34. Say x is one of the numbers that is multiplied by a factor 3. Thus, the new sum of the 5 numbers = 34 - x + 3x = 34 + 2x

Thus, the revised average of the 5 numbers = (34 + 2x)/5 = 9.2 => x = 6

The correct answer: E

Hope this helps!

-Jay
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by GMATGuruNY » Thu Aug 22, 2019 1:59 am
BTGmoderatorDC wrote:The average of 5 numbers is 6.8. If one of the numbers is multiplied by a factor of 3, the average of the numbers increases to 9.2. What number is multiplied by 3?

(A) 1.5
(B) 3.0
(C) 3.9
(D) 4.0
(E) 6.0
Sum of the original 5 numbers = (count)(average) = (5)(6.8) = 34
Sum of the resulting 5 numbers = (count)(average) = (5)(9.2) = 46
Increase in the sum = 46-24 = 12
Since this increase of 12 is yielded by multiplying one of the numbers by 3, 12 must be equal to the difference between the number tripled and the original number:
12 = 3x - x
12 = 2x
x = 6

The correct answer is E.
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by Scott@TargetTestPrep » Sat Aug 24, 2019 4:17 am
BTGmoderatorDC wrote:The average of 5 numbers is 6.8. If one of the numbers is multiplied by a factor of 3, the average of the numbers increases to 9.2. What number is multiplied by 3?

(A) 1.5
(B) 3.0
(C) 3.9
(D) 4.0
(E) 6.0

OA E

Source: Veritas Prep
The sum of the original 5 numbers is 6.8 x 5 = 34.

If we let k = the number that is multiplied by a factor of 3, then the new sum is 34 - k + 3k = 34 + 2k. We can create the equation:

(34 + 2k)/5 = 9.2

34 + 2k = 46

2k = 12

k = 6

Answer: E

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