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Bunuel
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If there are 13 boys in club X, what is the average age of these boys? 23 May 2020, 08:00
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E
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If there are 13 boys in club X, what is the average age of these boys?

(1) The oldest boy is 13 years old and the youngest boy is 9 years old.
(2) Eleven of the boys are either 10 years old or 11 years old.


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DS21210­
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E
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BrentGMATPrepNow
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If there are 13 boys in club X, what is the average age of these boys? 23 May 2020, 08:24
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Bunuel
If there are 13 boys in club X, what is the average age of these boys?

(1) The oldest boy is 13 years old and the youngest boy is 9 years old.
(2) Eleven of the boys are either 10 years old or 11 years old.
DS21210

Target question: What is the average age of the 13 boys?

When I SCAN the two statements, they both feel insufficient, AND I’m pretty sure I can identify some cases with conflicting answers to the target question. So, I’m going to head straight to……

Statements 1 and 2 combined
There are several scenarios that satisfy BOTH statements. Here are two:
Case a: The ages are {9, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 13}.
Case b: The ages are {9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 11, 13}
Since the two sets have DIFFERENT sums, we know that the averages will be DIFFERENT
Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer: E

Cheers,
Brent
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If there are 13 boys in club X, what is the average age of these boys? 03 Sep 2021, 22:20
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given: a1, a2, ..., a13
Ask: avrg = ?
(1) The oldest boy is 13 years old and the youngest boy is 9 years old.
=> Max = 13, min = 9
=> definitely insufficient
(2) Eleven of the boys are either 10 years old or 11 years old.
a2, a3,...,a12 = 10 or 11
=> definitely insufficient
(1) & (2): we still dont know the other 11 numbers are 10 or 11
=> insufficient
=> E

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If there are 13 boys in club X, what is the average age of these boys? 05 Aug 2024, 07:45
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BrentGMATPrepNow
Bunuel
If there are 13 boys in club X, what is the average age of these boys?

(1) The oldest boy is 13 years old and the youngest boy is 9 years old.
(2) Eleven of the boys are either 10 years old or 11 years old.
DS21210

Target question: What is the average age of the 13 boys?

When I SCAN the two statements, they both feel insufficient, AND I’m pretty sure I can identify some cases with conflicting answers to the target question. So, I’m going to head straight to......

Statements 1 and 2 combined
There are several scenarios that satisfy BOTH statements. Here are two:
Case a: The ages are {9, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 13}.
Case b: The ages are {9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 11, 13}
Since the two sets have DIFFERENT sums, we know that the averages will be DIFFERENT
Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer: E

Cheers,
Brent


Mine is a silly doubt
Since they have given it can be 11 or 10 after solving we get one decimal answer and one integer
So was wondering can average age be in decimals?

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Bunuel
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