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# In a school with 5 classes, each class has 2 students less then the

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Math Expert
Joined: 02 Sep 2009
Posts: 54544
In a school with 5 classes, each class has 2 students less then the  [#permalink]

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10 Jun 2016, 01:38
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Difficulty:

15% (low)

Question Stats:

86% (01:17) correct 14% (01:27) wrong based on 76 sessions

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In a school with 5 classes, each class has 2 students less then the previous class. How many students are there in the largest class if the total number of students at school is 95?

A. 17
B. 19
C. 21
D. 23
E. 25

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Joined: 06 Nov 2014
Posts: 1877
Re: In a school with 5 classes, each class has 2 students less then the  [#permalink]

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10 Jun 2016, 02:17
Bunuel wrote:
In a school with 5 classes, each class has 2 students less then the previous class. How many students are there in the largest class if the total number of students at school is 95?

A. 17
B. 19
C. 21
D. 23
E. 25

Total classes = 5
Total students = 95.

Average = 19
If the classes had average number of students: 19 19 19 19 19
Given case = 23 21 19 17 15

Hence number of students in the largest class = 23

Correct Option: D
Manager
Joined: 12 Oct 2012
Posts: 112
WE: General Management (Other)
Re: In a school with 5 classes, each class has 2 students less then the  [#permalink]

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10 Jun 2016, 02:58
IMO D = 23,

Do not know if there is any mathematical formula for this sequence. I solved by following method :

SUM = A+B+C+D+E
Let L be the class with largest number of students.

95 = L+L-2+L-4+L-6+L-8
95 = 5L - 20
23 = L.
Math Expert
Joined: 02 Aug 2009
Posts: 7589
Re: In a school with 5 classes, each class has 2 students less then the  [#permalink]

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10 Jun 2016, 03:07
1
Bunuel wrote:
In a school with 5 classes, each class has 2 students less then the previous class. How many students are there in the largest class if the total number of students at school is 95?

A. 17
B. 19
C. 21
D. 23
E. 25

The number of students is nothing but an AP with common difference of 2...
so the average of 5 classes = number of students in the middle class $$= \frac{95}{5} = 19$$..

Now largest number of students in a class = 19+2+2 = 23
D
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Joined: 21 Mar 2016
Posts: 519
Re: In a school with 5 classes, each class has 2 students less then the  [#permalink]

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10 Jun 2016, 03:59
2
Its an AP with common difference -2.

since the number of terms( number of classes ) = 5,
therefore, average = middle term = 3rd term = 95/5 = 19
largest term = 19+2+2 = 23
Intern
Joined: 17 Jul 2017
Posts: 8
Re: In a school with 5 classes, each class has 2 students less then the  [#permalink]

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21 Jul 2017, 07:15
Easy one as per give question 5 clases and suppose number of student in 1st class is x then every next is +2 so
x+x+2+x+4+x+6+x+8=95
5x+20=95
5x=75
x=15
now exmainer is asking for class that has max. students so
x+8=15+8=23
option D
Re: In a school with 5 classes, each class has 2 students less then the   [#permalink] 21 Jul 2017, 07:15
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