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The Average age of a class of 10 students is 15.

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stonecold
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The Average age of a class of 10 students is 15. [#permalink] New post   09 Dec 2016, 01:17
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The Average age of a class of 10 students is 15.An year later,one more student joins in.The average age of the class becomes 16 years. What is the age of the newest member of the class ?

A. 26 years
B. 22 years
C. 20 years
D. 18 years
E. 16 years
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E
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The Average age of a class of 10 students is 15. [#permalink] New post   09 Dec 2016, 11:29
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stonecold wrote:
The Average age of a class of 10 students is 15.An year later,one more student joins in.The average age of the class becomes 16 years. What is the age of the newest member of the class ?

A. 26 years
B. 22 years
C. 20 years
D. 18 years
E. 16 years


Total age of 10 students now is 150

Total age of 10 students after 1 year is 160

Now, \(\frac{160 + x}{11} = 16\)

Or, \(160 + x = 176\)

Or, \(x = 16\)

Hence, answer will be (E) 16
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Re: The Average age of a class of 10 students is 15. [#permalink] New post   09 Dec 2016, 22:13
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Here is my solution to this one.
Mean 1=> 15

After 1 year sum => 150+10=> 160
Mean 2(without new member)=> 160/10=> 16
Now since Mean 3(after new member joins in) i.e final mean is 16,the mean is not changing.
Hence the added value must be 16.

Hence E
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Re: The Average age of a class of 10 students is 15. [#permalink] New post   09 Dec 2016, 22:20
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We don't even have to calculate so much. If the average of x students this year is 15, the average of x students next year will be 16.

Even after the addition of the new student the average remains 16. So the new students age must be 16.

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Re: The Average age of a class of 10 students is 15. [#permalink] New post   14 Jul 2018, 19:32
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stonecold wrote:
The Average age of a class of 10 students is 15.An year later,one more student joins in.The average age of the class becomes 16 years. What is the age of the newest member of the class ?

A. 26 years
B. 22 years
C. 20 years
D. 18 years
E. 16 years


If the average age of a class of 10 students is 15 years old now, then a year later, the average age of the class will be 16 years old. Since the average age of the class is also 16 years old when a new student joins in, his or her age must be 16 years old also.

Answer: E
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The Average age of a class of 10 students is 15. [#permalink] New post   28 Apr 2020, 09:03
stonecold wrote:
The Average age of a class of 10 students is 15.An year later,one more student joins in.The average age of the class becomes 16 years. What is the age of the newest member of the class ?

A. 26 years
B. 22 years
C. 20 years
D. 18 years
E. 16 years


Given:
1. The Average age of a class of 10 students is 15.
2. An year later,one more student joins in.
3. The average age of the class becomes 16 years.

Asked: What is the age of the newest member of the class ?

Let the age of the newest member of the class be x years.

1. The Average age of a class of 10 students is 15.
2. An year later,one more student joins in.
1 year later, Average age of a class of 10 students will be 16 years
.
Total age of 11 students after 1 year = 10*16 + x = 160 + x = 16*11 = 176
x = 176 - 160 = 16 years

The age of the newest member of the class = 16 years

IMO E
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Re: The Average age of a class of 10 students is 15. [#permalink] New post   05 May 2020, 00:51
Total age of 10 students = 15*10 = 150

1 year later, Total age of 10 students = 16*10 = 160

Total age of 11 students = 16*11 = 176

Hence, age of new student = 176-160 = 16
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Re: The Average age of a class of 10 students is 15. [#permalink] New post   01 Oct 2021, 09:32
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Re: The Average age of a class of 10 students is 15. [#permalink]
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