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# The incomplete table above shows a distribution of scores for a class

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Joined: 26 Feb 2016
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Location: India
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The incomplete table above shows a distribution of scores for a class  [#permalink]

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15 Oct 2018, 12:07
2
00:00

Difficulty:

35% (medium)

Question Stats:

65% (01:59) correct 35% (02:21) wrong based on 69 sessions

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Attachment:

Class_Incomplete.JPG [ 13.48 KiB | Viewed 794 times ]

The incomplete table above shows a distribution of scores for a class of 20 students. If the average
(arithmetic mean) score for the class is 78, what score is missing from the table?

A. 73
B. 75
C. 77
D. 79
E. 81

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Joined: 02 Aug 2009
Posts: 7940
Re: The incomplete table above shows a distribution of scores for a class  [#permalink]

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15 Oct 2018, 18:57
pushpitkc wrote:
Attachment:
Class_Incomplete.JPG

The incomplete table above shows a distribution of scores for a class of 20 students. If the average
(arithmetic mean) score for the class is 78, what score is missing from the table?

A. 73
B. 75
C. 77
D. 79
E. 81

Total sum as per average of the class = 20*78=1560

Total sum as per the distribution of marks = 83*5+70*6+92*3+5x+64=415+420+276+64+5x=1175+5x

Both have to be same
So 1175+5x=1560.....5x=385....x=77

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Re: The incomplete table above shows a distribution of scores for a class  [#permalink]

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09 May 2019, 22:52
2
1
There is an alternative way using the difference method.
(83- 78)*5 = +25
(70-78)*6 = -48
(92-78)*3 = +42
(64-78)*1 = - 14
total difference = +5
the blank row can have total of 5 difference from average of 78. Since there are 5 students left so the value of the blank would be 78-5/5 = 77
Re: The incomplete table above shows a distribution of scores for a class   [#permalink] 09 May 2019, 22:52
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