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The youngest of 4 children has siblings who are 3, 5, and 8 years olde
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31 Mar 2021, 05:31
31 Mar 2021, 05:31
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The youngest of 4 children has siblings who are 3, 5, and 8 years older than she is. If the average (arithmetic mean) age of the 4 siblings is 21, what is the age of the youngest sibling?
A. 17
B. 18
C. 19
D. 21
E. 22
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
A. 17
B. 18
C. 19
D. 21
E. 22
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
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Joined: 10 Apr 2015
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Re: The youngest of 4 children has siblings who are 3, 5, and 8 years olde
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31 Mar 2021, 05:45
31 Mar 2021, 05:45
1
Carcass wrote:
The youngest of 4 children has siblings who are 3, 5, and 8 years older than she is. If the average (arithmetic mean) age of the 4 siblings is 21, what is the age of the youngest sibling?
A. 17
B. 18
C. 19
D. 21
E. 22
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
A. 17
B. 18
C. 19
D. 21
E. 22
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
Let y = the age of the youngest child
So, y + 3 = age of sibling who is 3 years older than the youngest child
y + 5 = age of sibling who is 5 years older than the youngest child
y + 8 = age of sibling who is 8 years older than the youngest child
The average (arithmetic mean) age of the 4 siblings is 21
This means: [y + (y+3) + (y+5) + (y+8)]/4 = 21
Multiply both sides by 4 to get: y + (y+3) + (y+5) + (y+8) = 84
Simplify: 4y + 16 = 84
Solve: y = 17
Answer: A
Cheers,
Brent
Retired Moderator
Joined: 16 Apr 2020
Status:Founder & Quant Trainer
Affiliations: Prepster Education
Posts: 1546
Given Kudos: 172
Location: India
WE:Education (Education)
The youngest of 4 children has siblings who are 3, 5, and 8 years olde
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31 Mar 2021, 06:37
31 Mar 2021, 06:37
Carcass wrote:
The youngest of 4 children has siblings who are 3, 5, and 8 years older than she is. If the average (arithmetic mean) age of the 4 siblings is 21, what is the age of the youngest sibling?
A. 17
B. 18
C. 19
D. 21
E. 22
A. 17
B. 18
C. 19
D. 21
E. 22
Let the age of the youngest sibling be \(x\)
Age of other siblings = \(x+3\), \(x+5\), and \(x+8\)
Given, \(\frac{x + (x+3) + (x+5) + (x+8)}{4} = 21\)
\(4x + 16 = 84\)
\(4x = 68\)
\(x = 17\)
Hence, option A
