Math Is Fun Forum

SomeCrazyAverageness

Guest

Re: How do i work out an average?

I'm having the hardest time figuring out this average.. I'm not bad at math, but my answers don't match up with the 4 they give me. Here's the question:

You work Monday through Friday from 7:00 am to 4:00 pm. On Monday, you sold $1,231.11 in gas and store product, on Tuesday you sold $843.09, on both Wednesday and Thursday you sold $1,425.25 and on Friday you sold $1,633.56. What is your sales average per day for this week?

Here are the answers
$1,286.25  $1,314.25  $1,311.65  $1,311.66

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: How do i work out an average?

Hi SomeCrazyAverageness;

Welcome to the forum!

So you would round down to $1311.65

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

SomeCrazyAverageness

Guest

Re: How do i work out an average?

Thank you, I solved it shortly after posting it. I must have been typing it in wrong

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: How do i work out an average?

Hi SomeCrazyAverageness;

No problem, I do that all the time.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

sidney hargreaves

Guest

Re: How do i work out an average?

hey can someone please help me out a little.

gotta find the average of these numbers:

80, 78, 60

and then to find out the average of these numbers too:

29,30,20

if anyone can help would be much appreciated:D

add them altogether and then divide by the number of numbers. I this case 3.

80 + 78 + 60 = 218 divided by 3 = 72.66

nonnyxxx

Guest

Re: How do i work out an average?

im still really stuck on my averages please help me!! i dont get it at all!!
eye colour    girls
blue/gray    1
blue/green    2
brown    3
hazel    0
grey    1
green    2
blue    6
i have to work out the average for girls eye colour and...
eye colour    boys
blue/gray    2
blue/green    0
brown    5
hazel    2
grey    0
green    0
blue    6
the average boys eye colour im really stuck please help me!!:( thank you!

Bob

Administrator

Registered: 2010-06-20

Posts: 10,643

Re: How do i work out an average?

hi nonnyxxx

Welcome to the forum.

Average for eye colour?  Not the 'mean' then; it wouldn't make sense.

I think you need to tell us more about this.

If it's a question (from a book or homework), then please state the question exactly as written.

If it's part of a project or coursework, then what are the requirements?  eg.  Pick a subject to investigate; collect some data; use statistics to describe what you have found out.

Post back and I'll try to help you.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

GOVINDH

Member

Registered: 2012-05-23

Posts: 1

Re: How do i work out an average?

I love this forum!

Bob

Administrator

Registered: 2010-06-20

Posts: 10,643

Re: How do i work out an average?

hi GOVINDH

Welcome to the forum!

This thread is one of MIF's most popular.  That is because if you 'google'

"How do I work out an average"

it is the number one hit.

Freelancer_Man  asked this in 2005 and members have been helping people with this topic ever since.

Amazing isn't it ?

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: How do i work out an average?

Hi GOVINDH;

Welcome to the forum!

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Brena

Guest

Re: How do i work out an average?

Hi;

I think you are all doing a fine job.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,643

Re: How do i work out an average?

Thanks you Brena.

Welcome to the forum!

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: How do i work out an average?

At the risk of sounding irrespectful to some, it seems bots have become more believable.

---

“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,643

Re: How do i work out an average?

hi Stefy,

Are you saying I've been talking to a bot?

eeekkk!  And she sounded so sweet. 

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: How do i work out an average?

She is sweet. And I haven't claimed she is a bot. I leave all conclusions to you..

---

“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: How do i work out an average?

Hi Brena;

Thanks for those kind words. You have really touched my heart.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

noelevans

Member

Registered: 2012-07-20

Posts: 236

Re: How do i work out an average?

Hi!

Here's an interesting approach to averaging.  Averages work similar to game scores.  Let the Home
team be on top and the Visitors on the bottom, supposing that we are dealing with football.  By
quarters suppose we have:
                    1st Quarter  2nd Quarter  3rd Quarter  4th Quarter   Totals
Home Team         7                 3                  14                6             30
       Visitors        3                 6                    7                7             23

We can write this more concisely as "scores" as follows:
                            7 + 3 +14 + 6     30
                            ~   ~   ~~   ~ = ~~   so the Home team won by 7 points.
                            3 + 6 + 7  + 7     23
Note that we are interested in the difference not the quotient of the two numbers, hence we use
the "~" to distinguish these from fractions which use the "-" or "/".

Now averages work similarly.  To average test scores of 80, 70 and 90 we obtain
                                    80  + 70 +  90     240                                        80
                                    ~~    ~~    ~~ = ~~~ which reduced by 3 gives ~~.
                                     1   +  1  +   1       3                                           1

The reducing is like asking what same score should be made on all three tests to get 240 points.
Obviously it is 80, 80 and 80 (which is the 240 divided by 3).

Now for a more difficult question we could ask what must  one average on the next two tests
to raise the overall 5 test average to 85?

                               80 + 70 + 90 + x +  x     240 + 2x       85
                               ~~   ~~   ~~    ~    ~  = ~~~~~~  =  ~~
                                 1 +  1  +  1 +  1 + 1           5              1

We set the sum equal to the desired five-test average.
Cross multiplication of the last two expressions yields 240+2x = 425
                                                                                     2x = 185
                                                                                       x = 92.5
Of course it is not likely that one would make 92.5 or each of the two tests.  More likely it would
occur as 92 and 93,  or 91 and 94,  or 90 and  95, etc.

The idea and notation of "scores" also works well with some other types of algebra word
problems, for example mixture problems and some rate/time/distance problems.
(Scores are to signed numbers as fractions are to rational numbers.  Fractions can be viewed
as "pre-rational numbers."  So scores can be viewed as "pre-signed numbers."
                                                                                                     0  1   2  3
   .5 corresponds to {1/2, 2/4, 3/6, ...}  whereas  -2 corresponds to { ~, ~, ~, ~, ...}
                                                                                                     2  3   4  5
                                                                                                     2  3   4  5
   2. corresponds to {2/1, 4/2, 6/3, ...}  whereas +2 corresponds to { ~, ~, ~, ~, ...}
                                                                                                     0  1   2  3
-2 is like the Home team being 2 behind and +2 is like the Home team being 2 ahead.

Example of a rate/time/distance problem:
   A man made a trip in two legs.  The first leg he went two miles in 3 hours and the second leg
he went 3 miles in 4 hours (pushing his car perhaps!).  What was his average speed on the trip?
                                                                 2mi       3mi
If we treat these ratios as fractions we have  ---- and ---- .  If we add, subtract, multiply or
                                                                 3hr        4hr
divide these fractions, none of the results are what we need to solve the problem.  On the other
hand if we treat them as scores we get
       2 + 3     5mi                                                    5/7 mi 
       ~    ~ = ~~~  and reducing this by 7 we obtain  ~~~~ ; that is, 5/7 mph.
       3 + 4     7hr                                                       1 hr

So this problem which is difficult for many people to figure out is only TWO steps.
1)  Add the scores and 2) reduce by the bottom number to get 1hr in the bottom.

An additional question: How long should a 3rd leg of 5mi take to raise the 3leg average to 1mph?
      2 + 3 + 5     1                   10      1
      ~   ~    ~ =  ~  becomes  ~~~ = ~  on cross multiplying becomes 7+x=10 so x = 3hrs.
      3 + 4 + x     1                  7+x     1

The language of fractions is the wrong language to work this kind of problem as well as averages.
We probably compare two numbers by differences as much as or more than we do as quotients.
The language of fractions is available for the quotient comparisons.
The language of scores for difference comparisons is analogous.

Here I am getting a bit "long winded" but one more observation might be helpful.

The idea of WEIGHTED averages works well with scores also.  For example if we have
three 90's and two 80's and a 70 to average we can write out all six scores individually and
add them or we can write
        x 90   +    x 80   +  70       270  +   160  +  70      500                           500/6       83.3
      3   ~~      2   ~~      ~~  = ~~~      ~~~     ~~  = ~~~ which reduces to ~~~~  = ~~~~
        x  1    +    x  1    +  1         3     +    2    +   1         6                              5/5           1
Then we might ask how low an average can we get on the next 4 tests to keep at least an 80
average on the ten tests altogether.
                   x  z              4z                                      80                    500+4z     80
Just add in  4   ~; that is, ~~ and set the total equal to ~~ and solve:   ~~~~~ = ~~
                   x  1              4                                        1                        10           1

500+4z = 800 so 4z = 300 so z = 300/4 = 75.

Grade point averages used so much at colleges are basically weighted averages also.

Scores are a "whole different ball game" so to speak.   

---

Writing "pretty" math (two dimensional) is easier to read and grasp than LaTex (one dimensional).
LaTex is like painting on many strips of paper and then stacking them to see what picture they make.

ralph

Guest

Re: How do i work out an average?

Thankyou very much Ganesh!

I don't know much maths, but I needed to work out an average and it took me 10 seconds to find this on google. Thankyou!

yeh same thanks

ralph

Guest

Re: How do i work out an average?

hi Stefy,

Are you saying I've been talking to a bot?

eeekkk!  And she sounded so sweet. 

Bob

what is a moderator:lol:

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: How do i work out an average?

Hi ralph;

A moderator is someone who monitors the content of the posting that the forum receives.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

noelevans

Member

Registered: 2012-07-20

Posts: 236

Re: How do i work out an average?

Hi MIF!

I was checking out "The Mean Machine" and I couldn't get it to clear out the previous set of data.
It kept bringing in values from the previous set of data.  Am I missing something here about how
to clear the data before entering a new set of data?

I was hitting "Enter" on the keyboard instead of clicking "go".  When I hit "enter" it just  cleared
all the values in the data window, but didn't do the calculation,  Might that have something to do
with it?

Last edited by noelevans (2012-11-04 14:36:28)

---

Writing "pretty" math (two dimensional) is easier to read and grasp than LaTex (one dimensional).
LaTex is like painting on many strips of paper and then stacking them to see what picture they make.

ihtemthsbtneedtoasksmthng

Member

Registered: 2012-12-09

Posts: 6

Re: How do i work out an average?

I've got my mock exams tomorrow and I've managed to find the paper online on emaths. I get how to work out the average and everything but it's in a table so I'm not entirley sure how to work it out. Here it is:

Place Season Mean rainfall Number of months Months
A: Dry-10cm per month 8 Jan to Aug
Wet-20cm per month 4 Sept to Dec
B: Dry 5cm per month 10 July to Apr
Wet 50cm per month 2 May to June

ihtemthsbtneedtoasksmthng

Member

Registered: 2012-12-09

Posts: 6

Re: How do i work out an average?

do you just add the 1O, 2O, 5 and 5O together? ahahah i spent 5 minutes working out the mean again..its actually unbelievable how dumb i am..how am i even in 2/8 sets in maths?

Bob

Administrator

Registered: 2010-06-20

Posts: 10,643

Re: How do i work out an average?

stay online I'm just looking at this

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Bob

Administrator

Registered: 2010-06-20

Posts: 10,643

Re: How do i work out an average?

ok

see below

Is this the information?

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob