Math Is Fun Forum

survival

Member

Registered: 2011-04-03

Posts: 655

Help. Deviation, z scores and Data Values

Hello, i am working on more homework and cannot understand or maybe my brain is just fried from too many numbers.

First problem.:
The mean for a data set is 71. The standard deviation is 5, and the z-score is 1.04. Find the data value corresponding to the value of z.
Thanks and much appreciated.

If this can be worked with a calculator which i think it can, please tell me where to go on a TI-84.

gAr

Member

Registered: 2011-01-09

Posts: 3,482

Re: Help. Deviation, z scores and Data Values

Hi,

Is this what you need?

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"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

survival

Member

Registered: 2011-04-03

Posts: 655

Re: Help. Deviation, z scores and Data Values

Thanks, can you tell me how you got it so i can understand it for the test? I am in a statistical/probability class and this looks like Algebra. I do not know Algebra very well, although I did pass it last semester. It is a blur.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Help. Deviation, z scores and Data Values

Hi survival;

That is the formula. Now you want to solve for x. That means getting it on one side all by itself.
Plug in the values you are given.

Multiply both sides by 5

Do you follow so far?

---

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.

survival

Member

Registered: 2011-04-03

Posts: 655

Re: Help. Deviation, z scores and Data Values

It's the correct answer for sure.

Truthfully, i don't know if i understand it or not. I am going to post more problems. I wish I had found this forum last semester when I had Algebra. It's a wonderful forum with genius mathematicians.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Help. Deviation, z scores and Data Values

Hi survival;

We are not done with that problem yet. Where are you having problems with post # 4?

---

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.

survival

Member

Registered: 2011-04-03

Posts: 655

Re: Help. Deviation, z scores and Data Values

Okay, I reworked that one and understand it better; I think. Both sides are being multiplied then divided by five.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Help. Deviation, z scores and Data Values

Okay:

After doing the multiplication on the left and noticinig that the 5's cancel on the right we get:

Do you follow that?

---

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.

survival

Member

Registered: 2011-04-03

Posts: 655

Re: Help. Deviation, z scores and Data Values

yes. Can this one be solved from the graph you posted yesterday?
Find the per cent of the total area under the standard normal curve between the following z-scores.

z= -1.4 and z = -0.65
The per cent of the total area between z= -1.4 and z = -.65 is _____%.
Thanks.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Help. Deviation, z scores and Data Values

Hi;

That graph is not fine enough to do the job. Let me solve it first.

That is equal to 17.7%

---

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.

survival

Member

Registered: 2011-04-03

Posts: 655

Re: Help. Deviation, z scores and Data Values

Thanks, it showed 18%. It rounded it up. It gave me another one when I missed it.
z= - 1.4 and z = - 0.8 is ___%.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Help. Deviation, z scores and Data Values

Hi survival;

13.1%

---

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.

survival

Member

Registered: 2011-04-03

Posts: 655

Re: Help. Deviation, z scores and Data Values

I don't know why but it's not taking that answer. The online homework site is picky about how it wants the answer.
It just said to round to the nearest integar.

survival

Member

Registered: 2011-04-03

Posts: 655

Re: Help. Deviation, z scores and Data Values

Hello, it took 13. Thank you so very much.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Help. Deviation, z scores and Data Values

Then say 13%. Now how about seeing how these are done?

---

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.

survival

Member

Registered: 2011-04-03

Posts: 655

Re: Help. Deviation, z scores and Data Values

z = -1.6 and z = - 0.8 is ____%.
How do you do this? Can u explain it for me. Thanks.

survival

Member

Registered: 2011-04-03

Posts: 655

Re: Help. Deviation, z scores and Data Values

yes, i want to know how they are solved. I have a test on five chapters next Friday.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Help. Deviation, z scores and Data Values

Go here and take a look at this chart.

http://www.regentsprep.org/Regents/math … ZChart.htm

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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.

survival

Member

Registered: 2011-04-03

Posts: 655

Re: Help. Deviation, z scores and Data Values

So this is a bit of Trig. and Algebra combined or what is it? And the chart is great, but how do i find my way around it, mean, stand. dev., percentage. etc? I don't mean to sound stupid.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Help. Deviation, z scores and Data Values

Just follow what I say and you will be fine.

Look at the chart and find -1.6 check the box. You will see a .0548 then go to the box -.8 you will see .2119

Subtract the .0548 from the .2119 and you get what?

---

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.

survival

Member

Registered: 2011-04-03

Posts: 655

Re: Help. Deviation, z scores and Data Values

Thank you so much. Everything helps push me along. Test next week on this stuff.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Help. Deviation, z scores and Data Values

Hi survival;

What did you get for an answer? And let us do 45 or 50 more problems.

---

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.

survival

Member

Registered: 2011-04-03

Posts: 655

Re: Help. Deviation, z scores and Data Values

Hello, and good morning. I don't remember since i typed it in and it was correct last night. The table was very helpful, if I can read it accurately.
How do I differentiate between below the mean and below it. I know to the left is negative and right positive.

I am working on more math. So many things to ask. I have a quiz on this stuff than another test online.

survival

Member

Registered: 2011-04-03

Posts: 655

Re: Help. Deviation, z scores and Data Values

Correction above the mean and below it.

survival

Member

Registered: 2011-04-03

Posts: 655

Re: Help. Deviation, z scores and Data Values

I will post a problem in a new topic. I have been getting a few right this morning, so there is light at the end of the road. haha