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# A set of data contains 5 different numbers whose average is 8.8. After

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Math Expert
Joined: 02 Sep 2009
Posts: 49303
A set of data contains 5 different numbers whose average is 8.8. After  [#permalink]

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20 May 2017, 05:24
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Difficulty:

15% (low)

Question Stats:

75% (00:58) correct 25% (00:43) wrong based on 164 sessions

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A set of data contains 5 different numbers whose average is 8.8. After one of the numbers in the set is doubled, the average becomes 11.2. What is the value of that number?

A. 2.4
B. 4
C. 4.8
D. 6
E. 12

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Re: A set of data contains 5 different numbers whose average is 8.8. After  [#permalink]

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20 May 2017, 06:16
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Bunuel wrote:
A set of data contains 5 different numbers whose average is 8.8. After one of the numbers in the set is doubled, the average becomes 11.2. What is the value of that number?

A. 2.4
B. 4
C. 4.8
D. 6
E. 12

Original average of 5 numbers = 8.8
Original sum = 8.8 * 5= 44
After one of numbers is doubled , new average = 11.2
New sum = 11.2*5 = 56
Difference = 56-44 = 12
Value of number that was doubled = 12

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Re: A set of data contains 5 different numbers whose average is 8.8. After  [#permalink]

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20 May 2017, 07:19
Average = Sum/n

8.8 = Sum/5 or Sum = 8.8*5 = 44

Let the number which is doubled be x. So when we make x as 2x, basically we have added 'x' only to the initial sum
So, New Sum = 44+x
New Average = (44+x)/5 = 11.2
Solve to get 44+x = 56 or x = 12.

So the number is 12. hence E
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Re: A set of data contains 5 different numbers whose average is 8.8. After  [#permalink]

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25 May 2017, 22:59
Actual average of 5 numbers = 8.8
Sum = 8.8 * 5= 44
After one of numbers is doubled , new average = 11.2
New sum = 11.2*5 = 56

Value of number that was doubled = 12
ans E
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Re: A set of data contains 5 different numbers whose average is 8.8. After  [#permalink]

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31 May 2017, 19:08
1
1
Bunuel wrote:
A set of data contains 5 different numbers whose average is 8.8. After one of the numbers in the set is doubled, the average becomes 11.2. What is the value of that number?

A. 2.4
B. 4
C. 4.8
D. 6
E. 12

We’ll use this formula: average = sum/quantity, or average x quantity = sum. Thus, the initial sum of the numbers is 8.8 x 5 = 44.

When 1 particular number is doubled, the new average is 11.2, and thus the new sum is 11.2 x 5 = 56.

Since the difference between the new sum and the initial sum should equal the number that is doubled, the value 56 - 44 = 12 must be the number that is doubled.

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Re: A set of data contains 5 different numbers whose average is 8.8. After  [#permalink]

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21 Aug 2018, 09:54
$$(11.2-8.8)*5 = 2.4*5= 12$$

Re: A set of data contains 5 different numbers whose average is 8.8. After &nbs [#permalink] 21 Aug 2018, 09:54
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