# Mean number problem

1. Apr 20, 2007

### Trail_Builder

hi, i have this mean number problem that appears on my past paper and am kinda stuck. would like a gentle push in the right direction :D thnx

1. The problem statement, all variables and given/known data

Ibrahim has two lists of numbers.
The mean of the numbers in the first list is p.
The mean of the numbers in the second list is q.

Ibrahim combines the two lists into one new list of numbers.

Ibrahim says "The mean of the new list of numbers is equal to $$\frac{p+q}{2}$$"

One of the two conditions must be satisfied for Ibrahim to be correct.

qu) Write down each of these conditions.

2. Relevant equations

3. The attempt at a solution

Condition 1: The number of numbers in list 1 must be the same as list 2.

Condition 2:???

I'm stuck, lol. i can't find a second condition. I have had a few ideas, such as the number of numbers being the same of the mean - but that didn't really owrk when i looked further into it.

I also, had the idea of the lists both being with only 1 number, but that is just one case of condition 1.

Would i be right in saying the list had to contain positive values? or something along those lines? I couldn't really decide whether or not that would be right.

I may may missed something obvious, yet inconspicuous, that i might have taken for granted?

just a lil push in the right direction will help :D thnx

2. Apr 20, 2007

### enricfemi

:rofl: :rofl: :rofl: :rofl:
hi,
you go to a wrong way, how do you know the Condition 1

3. Apr 20, 2007

### Dick

Suppose the two means are the same.

4. Apr 20, 2007

### Trail_Builder

oooo i see, thnx :D

5. Apr 20, 2007

### enricfemi

this problem is not difficulty ,you can't find something you want because you
are live in water ,just like fish(as somebody said).