Math Is Fun Forum

nancy2007

Member

Registered: 2007-02-20

Posts: 1

Need help on percentage.

Hi,
How do I calculate the top 20% highest grade for the following students:

A got 99
B got 93
C got 91
D got 85
E got 60
F got 50

Thank you very much for your help.
Nancy

Jai Ganesh

Administrator

Registered: 2005-06-28

Posts: 48,421

Re: Need help on percentage.

Nancy,
The question doesn't seem clear enough, I am unable to understand.
Is the score given in percentage?
What are you expected to calculate?

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It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

mykel

Member

Registered: 2007-02-11

Posts: 4

Re: Need help on percentage.

That would be quite difficult w/o the use of variables (assigning each grade a variable and then sorting numerically).  I can think of a solution by writing a computer program, but I'm not sure how I'd do it mathematically in a cut and dried method.  Mind you, I'm just starting Trig.

lightning

Real Member

Registered: 2007-02-26

Posts: 2,060

Re: Need help on percentage.

did you know that 111,111,111x111,111,111=12345678987654321

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mykel

Member

Registered: 2007-02-11

Posts: 4

Re: Need help on percentage.

lightning

Real Member

Registered: 2007-02-26

Posts: 2,060

Re: Need help on percentage.

what it's true and wise i think

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mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: Need help on percentage.

True and wise it may be, but on-topic it is not.
Sorry to be a party-pooper, but next time you have an amazing fact like this to share, please put it in a new topic, preferably also on a different board.

"This is Cool" perhaps, or maybe Dark Discussions.

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Why did the vector cross the road?
It wanted to be normal.

lightning

Real Member

Registered: 2007-02-26

Posts: 2,060

Re: Need help on percentage.

sorry what is this

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bluestar9cn

Member

Registered: 2007-03-04

Posts: 4

Re: Need help on percentage.

I'm not very sure about your problem.
but, I tried, maybe this is what your want.

100*(100-20)%=80

you have 4 students above 80.

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: Need help on percentage.

How do I calculate the top 20% highest grade for the following students:

A got 99
B got 93
C got 91
D got 85
E got 60
F got 50

For six people, the top 20% is the top [0.2×6] = [1.2] = 1 people (or rather person). ([x] denotes the greatest integer less than or equal to x.)

So only 1 person in the any group of 6 people can be in the top 20%; in this case, it’s A.

mykel

Member

Registered: 2007-02-11

Posts: 4

Re: Need help on percentage.

For six people, the top 20% is the top [0.2×6] = [1.2] = 1 people (or rather person). ([x] denotes the greatest integer less than or equal to x.)

So only 1 person in the any group of 6 people can be in the top 20%; in this case, it’s A.

Perhaps something like this?

((99+93+91+85+60+50)/6 )  *1.2

(1/6) <-for the six grades

(99+93+91+85+60+50) <- add the grades

* 1.2 <- to get the top 20%

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: Need help on percentage.

I'm not sure that that would work.
If you wanted to find the top 10% instead, then by your method you'd multiply the mean by 1.1 instead of 1.2.

But that would lower the result, and that doesn't make sense.

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Why did the vector cross the road?
It wanted to be normal.

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: Need help on percentage.

A statistic like top 20% or top 10% would be much more relevant when there’s a much larger group (say, 100 or more). 6 is really too small a group.