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# 20 students including Tom take a test and Tom gets 5.8 pts higher than

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Joined: 14 Nov 2016
Posts: 1322
Location: Malaysia
20 students including Tom take a test and Tom gets 5.8 pts higher than  [#permalink]

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Updated on: 19 Feb 2017, 21:17
6
00:00

Difficulty:

45% (medium)

Question Stats:

65% (02:08) correct 35% (02:34) wrong based on 96 sessions

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20 students including Tom take a test and Tom gets 5.8 pts higher than their average score. If the teacher gives all the 20 students an additional 10 pts question and Tom is the only one who solved it correctly, how many pts is tom’s average score higher than the average score of the total 20 students?

A. $$6.2$$
B. $$10.4$$
C. $$10.5$$
D. $$15.3$$
E. $$16.2$$

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Originally posted by hazelnut on 19 Feb 2017, 21:16.
Last edited by Bunuel on 19 Feb 2017, 21:17, edited 1 time in total.
Edited the question.
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Joined: 14 Nov 2014
Posts: 632
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Re: 20 students including Tom take a test and Tom gets 5.8 pts higher than  [#permalink]

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19 Feb 2017, 22:14
ziyuenlau wrote:
20 students including Tom take a test and Tom gets 5.8 pts higher than their average score. If the teacher gives all the 20 students an additional 10 pts question and Tom is the only one who solved it correctly, how many pts is tom’s average score higher than the average score of the total 20 students?

A. $$6.2$$
B. $$10.4$$
C. $$10.5$$
D. $$15.3$$
E. $$16.2$$

10 marks question correct --Avg will get increased by 0.5(as 20 student are there and all got incorrect) , so diff for tom will get dec by 0.5 ,
so now tom avg is 5.3 higher + 10 marks for the correct answer
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Joined: 27 May 2012
Posts: 671
20 students including Tom take a test and Tom gets 5.8 pts higher than  [#permalink]

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23 Jan 2018, 03:26
hazelnut wrote:
20 students including Tom take a test and Tom gets 5.8 pts higher than their average score. If the teacher gives all the 20 students an additional 10 pts question and Tom is the only one who solved it correctly, how many pts is tom’s average score higher than the average score of the total 20 students?

A. $$6.2$$
B. $$10.4$$
C. $$10.5$$
D. $$15.3$$
E. $$16.2$$

When the question says " Tom gets 5.8 Pts higher than THEIR average score " does it mean Toms score is 5.8 pts higher than the average of all the 20 students or 5.8 Pts higher than the avg of the remaining 19 students ?
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- Stne

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Re: 20 students including Tom take a test and Tom gets 5.8 pts higher than  [#permalink]

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04 Feb 2018, 00:42
Bunuel

Thanks
Math Expert
Joined: 02 Aug 2009
Posts: 7212
Re: 20 students including Tom take a test and Tom gets 5.8 pts higher than  [#permalink]

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04 Feb 2018, 03:52
3
1
ektasahani wrote:
Bunuel

Thanks

You can do it with various method..
Logically...
Let the AVERAGE be 10, so Tom score = 10+5.8=15.80
Since only Tom answers the question correctly, the total increases by only 10..
So the AVERAGE increases by 10/20=0.5 as 10 gets distributed among all 20.. so new AVERAGE = 10.50

But the score of T now goes up by 10 , so new score = 15.8+10=25.80..

So the difference now is 25.80-10.50=15.30..

D
Hope it helps
stne, average includes Tom's marks as their refers to all 20..
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1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

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Joined: 02 Aug 2009
Posts: 7212
20 students including Tom take a test and Tom gets 5.8 pts higher than  [#permalink]

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12 Feb 2018, 00:11
1
hazelnut wrote:
20 students including Tom take a test and Tom gets 5.8 pts higher than their average score. If the teacher gives all the 20 students an additional 10 pts question and Tom is the only one who solved it correctly, how many pts is tom’s average score higher than the average score of the total 20 students?

A. $$6.2$$
B. $$10.4$$
C. $$10.5$$
D. $$15.3$$
E. $$16.2$$

Algebraic approach..

Let x be the average...
So Tom's marks =x+5.8

Now only Tom answers a 10 marks question correctly..
So new total =20x+10 and average = $$\frac{20x+10}{20}=x+0.5$$
Tom's marks now = x+5.8+10=x+15.8

Difference= $$x+15.8-(x+0.5)=15.3$$
D

You can also take x as some value if you are not comfortable with variable x..
Remember x does not effect the question at all, as it gets subtracted out.
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

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20 students including Tom take a test and Tom gets 5.8 pts higher than &nbs [#permalink] 12 Feb 2018, 00:11
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