Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

**SomeCrazyAverageness****Guest**

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: 109,435

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.**

Offline

**SomeCrazyAverageness****Guest**

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: 109,435

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.**

Offline

**sidney hargreaves****Guest**

Charlotte wrote:

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**

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 bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,925

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

Offline

**GOVINDH****Member**- Registered: 2012-05-23
- Posts: 1

I love this forum!

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,925

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

Offline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,435

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.**

Offline

**Brena****Guest**

Hi;

I think you are all doing a fine job.

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,925

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

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,030

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.

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,925

hi Stefy,

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

eeekkk! And she sounded so sweet.

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,030

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.

Offline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,435

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.**

Offline

**noelevans****Member**- Registered: 2012-07-20
- Posts: 236

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.

Offline

**ralph****Guest**

Mark.S wrote:

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**

bob bundy wrote:

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: 109,435

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.**

Offline

**noelevans****Member**- Registered: 2012-07-20
- Posts: 236

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.

Offline

**ihtemthsbtneedtoasksmthng****Member**- Registered: 2012-12-09
- Posts: 6

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

Offline

**ihtemthsbtneedtoasksmthng****Member**- Registered: 2012-12-09
- Posts: 6

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?

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,925

stay online I'm just looking at this

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,925

ok

see below

Is this the information?

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Offline