Math homework help needed

[Ellen aka Snow White]

Ok here is the problem:

FInd what number n equals

3, 5, 11, 19, 5, 15, 17, n

Range = 16 (difference between low # and high #0

Mode = 5 (number that occurs most often)

Median = 8 (middle number when put in line order)

Mean = 10 (average of all numbers)


HELP! I am embarrassed to say this is a 5th grade math problem! I think I know the answer but the teacher is saying (determined) I am wrong and she is right. It was 20 points off for this one problem! Please let me know what you get!

 

[CRB#33]

I believe the answer is 5.

 

[CarolG]

If the mean is 10, then I also get n=5.

The sum of the seven given numbers is 75, so (75 + n) / 8 = 10

What does the teacher say is the correct answer?

 

[Lanshark]

The answer is 5

If the mean is 10 and there are 8 numbers their total must add to 80. The total of all numbers given is 75 therefore n must equal 5.

 

[Rajah]

I agree -- 5.

 

[Karel]

42. It's always the answer to life, the universe and everything.

 

[FOJMO]

My head hurt even BEFORE I read this thread...

 

[Simba's Mom]

Well, I'm a tenth grade math teacher (tell her that's double her grade) and I also think it's five. We could get into a big argument here (LOL)! I say she's WRONG! Stick to your guns!

 

[Abbie]

Hello,

I'm a long-time lurker but I'm gonna jump in here and say the answer is 8......

If the median is 8, there has to be an 8 in the sequence somewhere. This still makes the mean 10.4, which is close enough to 10, right?

Back to lurkdom for me.....

 

[helenabear]

Originally posted by Abbie
Hello,

I'm a long-time lurker but I'm gonna jump in here and say the answer is 8......

If the median is 8, there has to be an 8 in the sequence somewhere. This still makes the mean 10.4, which is close enough to 10, right?

Back to lurkdom for me.....

I was thinking the same thing myself... except then I realized there was an even amount of numbers and you take the average of the two to get the mean and 5 and 11 divided by two is 8

And Abbie, come out of lurkdom more... it can be fun

 

[Saffron]

I'm not even going to attempt the problem, I'm too busy eating cashews and trying to type. (Yeah, that's it, I think they'll buy that answer. ) I just wanted to say hi to Abbie!

Hi Abbie!

 

[Experiment626]

Both by calculating the mean (as described in other posts) and looking at the median the answer would be 5.

If the median is 8, there has to be an 8 in the sequence somewhere.

Not quite. According to the mw dictionary:

http://www.britannica.com/dictionary?book=Dictionary&va=median

"<b>def. median:</b> a value in an ordered set of values below and above which there is an equal number of values or which is the arithmetic mean of the two middle values if there is no one middle number"

Since there are 8 numbers, the median here is really the 'arithmetic mean' (or average) between the 4th and the 5th number. If you plug in 5 into the list you get the following in order:

3,5,5,5,11,15,17,19

so the median is the middle of 5 and 11 == 8

I pick 5.

 

[CRB#33]

Well the problem is if the median is 8, and I understand your logic, then the mean of 10 can't be right.

I'll have to stick with 5.

I'm curious what the teacher told you.

 

[Lanshark]

I'm also wondering what the teacher said.