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The average (arithmetic mean) of seven numbers is 9 and the average of
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25 May 2023, 22:44
25 May 2023, 22:44
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The average (arithmetic mean) of seven numbers is 9 and the average of three of these numbers is 5. What is the average of the other four numbers?
A. 4
B. 5
C. 7
D. 10
E. 12
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A. 4
B. 5
C. 7
D. 10
E. 12
Post A Detailed Correct Solution For The Above Questions And Get A Kudos.
Question From Our Project: Free GRE Prep Club Tests in Exchange for 20 Kudos
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Re: The average (arithmetic mean) of seven numbers is 9 and the average of
[#permalink]
27 May 2023, 22:43
27 May 2023, 22:43
1
Expert Reply
To find the average of the other four numbers, we can use the concept of weighted averages.
Let's assume the sum of the seven numbers is represented by S.
According to the information given, the sum of the seven numbers is 9 multiplied by 7 (since the average of seven numbers is 9):
S = 9 * 7 = 63.
We are also told that the average of three of these numbers is 5. Let's call these three numbers A, B, and C.
The sum of these three numbers is 5 multiplied by 3 (since the average of three numbers is 5):
A + B + C = 5 * 3 = 15.
Now, we need to find the sum of the other four numbers. Let's call these four numbers D, E, F, and G.
The sum of these four numbers can be calculated as:
D + E + F + G = S - (A + B + C)
= 63 - 15
= 48.
Finally, to find the average of the other four numbers, we divide the sum by the count of numbers, which is 4:
Average = (D + E + F + G) / 4
= 48 / 4
= 12.
Therefore, the average of the other four numbers is 12.
The answer is (E) 12.
Let's assume the sum of the seven numbers is represented by S.
According to the information given, the sum of the seven numbers is 9 multiplied by 7 (since the average of seven numbers is 9):
S = 9 * 7 = 63.
We are also told that the average of three of these numbers is 5. Let's call these three numbers A, B, and C.
The sum of these three numbers is 5 multiplied by 3 (since the average of three numbers is 5):
A + B + C = 5 * 3 = 15.
Now, we need to find the sum of the other four numbers. Let's call these four numbers D, E, F, and G.
The sum of these four numbers can be calculated as:
D + E + F + G = S - (A + B + C)
= 63 - 15
= 48.
Finally, to find the average of the other four numbers, we divide the sum by the count of numbers, which is 4:
Average = (D + E + F + G) / 4
= 48 / 4
= 12.
Therefore, the average of the other four numbers is 12.
The answer is (E) 12.
gmatclubot
Re: The average (arithmetic mean) of seven numbers is 9 and the average of [#permalink]
27 May 2023, 22:43
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