Statistics Assignment due in tomorrow please help!

i_need_maths_help! · 2010-01-20 07:55:21

Hi

my stats assignment is due in tomorrow and ive started it but am soo stuck on several things

If anyone could help me with the following would be great !!!

How do I work out a variety of averages and measurements of dispersion?

I have this info:

salary number of employees
450<500 40
500<550 75
550<600 40
600<650 22
650<700 12
700<750 5
750<800 2

I have drawn a histogram for this and found out it is positively skewed and then thought I should work out the mid point, fx, cumulative frequency and cumulative % but don't know if I should of done this or how to work out the above things!

Please help me!!

me again · 2010-01-20 08:07:54

Thought it may help if I put in the table I have done:

Salary (£ per week) Freq (f) Mid Pt (x)    fx    fxx    cumm f    cumm %
450 but under 500 40    475    19000    9025000    40    20.40816327
500 but under 550 75    525    39375 20671875 115    58.67346939
550 but under 600 40    575    23000 13225000 155    79.08163265
600 but under 650 22    625    13750 8593750 177    90.30612245
650 but under 700 12    675    8100    5467500 189    96.42857143
700 but under 750 5    725    3625    2628125 194    98.97959184
750 but under 800 2    775    1550    1201250 196    100
Totals    196    108400 60812500

Thank you for looking

bobbym · 2010-01-20 10:40:42

Hi me again;

Are you asking for the mean and the standard deviation of your grouped data?

lou_needs_maths_help · 2010-01-20 20:58:35

Hi

I have done this

Mean 553.0612245 Var 4391.139109
Q1 455 St Dev 66.26567067
Median 480 Semi Interquartile Range 65
Q3 585 Minimum 450
Maximum 799
Range 349

But not sure if it is right?? handing it in in 3 hours! please help

bobbym · 2010-01-20 21:00:32

Hi lou_needs_maths_help;

Where is the data?

lou_needs_maths_help · 2010-01-20 21:05:49

all the information I have been given is above, thank you for trying to help I'm an events students so not very good at statistics!

bobbym · 2010-01-20 21:10:11

Hi

I have done this

Can you explain how you found the standard deviation or the mean without the data?

lou_needs_maths_help · 2010-01-20 21:16:55

To get the standard deviation I did the square root of the var?
to get the mean i did total fx/ total frequency - 108,440/196

Is that wrong?

bobbym · 2010-01-20 21:22:13

No, that is fine for the SD. But your mean is slightly off, please redo the division.

lou_needs_maths_help · 2010-01-20 21:29:06

oops! thank you! so do you think my sums are correct now for this question? have i done all I can do th show a variety of averagges and measures of dispersion?

Thank you so much for helping

bobbym · 2010-01-20 21:47:08

I think you are OK.

lou_needs_maths_help · 2010-01-20 21:49:32

Brilliant thank you!

bobbym · 2010-01-20 22:08:14

Whoa, whoa, hold on are you the same poster as at the top of this thread?

lou_needs_maths_help · 2010-01-20 22:10:29

yeah i am why does that mean it is wrong?

bobbym · 2010-01-20 22:15:43

No, but the different names confused the issue, the question is, when I asked you how you got the SD you said by taking the square root of the Variance. That is fine, I assumed you had been given the Variance. Now I see that you had to calculate the Variance from grouped data, are you sure you did that right?

lou_needs_maths_help · 2010-01-20 22:21:09

ohh yea sorry I wasnt a member last night when I first posted the question.
I got the variance from a complicated formula I found on an example page:

fxx/f - mean x mean

is that right?

bobbym · 2010-01-20 22:33:43

I hope that is right because there isn't time to compute it now.

lou_needs_maths_help · 2010-01-20 22:36:16

ok well it is in my notes so should be right i hope! thank you for your help!

bobbym · 2010-01-20 22:43:20

Good luck! Come back and tell me how you did.

Math Is Fun Forum

#1 2010-01-20 07:55:21

Statistics Assignment due in tomorrow please help!

#2 2010-01-20 08:07:54

Re: Statistics Assignment due in tomorrow please help!

#3 2010-01-20 10:40:42

Re: Statistics Assignment due in tomorrow please help!

#4 2010-01-20 20:58:35

Re: Statistics Assignment due in tomorrow please help!

#5 2010-01-20 21:00:32

Re: Statistics Assignment due in tomorrow please help!

#6 2010-01-20 21:05:49

Re: Statistics Assignment due in tomorrow please help!

#7 2010-01-20 21:10:11

Re: Statistics Assignment due in tomorrow please help!

#8 2010-01-20 21:16:55

Re: Statistics Assignment due in tomorrow please help!

#9 2010-01-20 21:22:13

Re: Statistics Assignment due in tomorrow please help!

#10 2010-01-20 21:29:06

Re: Statistics Assignment due in tomorrow please help!

#11 2010-01-20 21:47:08

Re: Statistics Assignment due in tomorrow please help!

#12 2010-01-20 21:49:32

Re: Statistics Assignment due in tomorrow please help!

#13 2010-01-20 22:08:14

Re: Statistics Assignment due in tomorrow please help!

#14 2010-01-20 22:10:29

Re: Statistics Assignment due in tomorrow please help!

#15 2010-01-20 22:15:43

Re: Statistics Assignment due in tomorrow please help!

#16 2010-01-20 22:21:09

Re: Statistics Assignment due in tomorrow please help!

#17 2010-01-20 22:33:43

Re: Statistics Assignment due in tomorrow please help!

#18 2010-01-20 22:36:16

Re: Statistics Assignment due in tomorrow please help!

#19 2010-01-20 22:43:20

Re: Statistics Assignment due in tomorrow please help!

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