S^2/c

[minnsy229]

The mean number of flowers per plant for Sample 1 = 6.44 and Sample 2 = 7.20
The estimated population standard deviation of number of flowers per plant Sample 1 = 1.51 and Sample 2 = 1.80

And Sample size for Sample 1 = 9 and Sample 2 = 20
Calculate S^2/c (the common population variance) for these data (to at least three places of decimals).

S^2/c = (This has to be one answer for all of the data!!!!)


______________________________________________________________
for sample one I worked out that the common population variance should be 3.038

and for sample two the common population variance should be 1.534


If these are correct, to work out the overall answer should I just add them together???

 

[mmm4444bot]

Calculate the common population variance for the following data

S^2/c =

I'm thinking that symbol c may be a subscript, not a denominator.

I'm also confused on why they use the symbol S² for population variance because S² is already used for sample variance.

The standard symbol for population variance is σ^2.

Here is a reference page that discusses population- and sample-variance formulas.

 

[minnsy229]

Additional info

Hi there


When answering the question I obviously entered it incorrectly and it has provided the following additional hint as well which I have attached to confirm the equation for the common population variance. Does that help?

 

[mmm4444bot]

NOTES:

You only need to post your requests for help once; we see everything. If you see no replies, please do not assume that you're being ignored.

Also, when you wish to contribute additional information to your thread, please do not edit it into your original post. Instead, use the [Reply to Thread] button to add your information as a new post.

---

Okay, I understand from your latest attachment that you have a formula for s_c^2 in terms of four numbers: n₁, n₂, s₁, and s₂

I'm not familiar with this formula, and I see no definition for symbol c in this exercise. Also, that formula does not use the \(\displaystyle \bar{x}\) data from the chart. Hence, I feel a bit apprehensive about the following suggestion, but here goes ...

You could try simple substitution, based on the data in the chart.

It's hard for me to read all of the chart, due to its small size (likely because you did not crop the image before attaching it). One of the variables listed looks like: s_n - 1. Is that correct?

If so, we may have the following, for sample 1:

s₁ - 1 = 1.51 which leads to s₁ = 2.51

n₁ = 9

Reason the same for symbols s₂ and n₂.

Plug into your formula all four numbers, and simplify.

Let us know what you think. :cool:

 

[minnsy229]

This is it close up

 

[minnsy229]

You are correct on the - yes, although it is small. I am doing this as a one off quiz so as its totally new to me I will need more help please

NOTES:

You only need to post your requests for help once; we see everything. If you see no replies, please do not assume that you're being ignored.

Also, when you wish to contribute additional information to your thread, please do not edit it into your original post. Instead, use the [Reply to Thread] button to add your information as a new post.

---

Okay, I understand from your latest attachment that you have a formula for s_c^2 in terms of four numbers: n₁, n₂, s₁, and s₂

I'm not familiar with this formula, and I see no definition for symbol c in this exercise. Also, that formula does not use the \(\displaystyle \bar{x}\) data from the chart. Hence, I feel a bit apprehensive about the following suggestion, but here goes ...

You could try simple substitution, based on the data in the chart.

It's hard for me to read all of the chart, due to its small size (likely because you did not crop the image before attaching it). One of the variables listed looks like: s_n - 1. Is that correct?

If so, we may have the following, for sample 1:

s₁ - 1 = 1.51 which leads to s₁ = 2.51

n₁ = 9

Reason the same for symbols s₂ and n₂.

Plug into your formula all four numbers, and simply.

Let us know what you think. :cool:

 

[mmm4444bot]

I am doing this as a one off quiz

I do not understand what this means.

as its totally new to me I will need more help please

Hmmm, I'm not sure whether you understood how we got the values for s₁ and n₁ enough to be able to find values for s₂ and n₂ yourself.

These boards are mostly for people who have some understanding of what they're doing but are stuck at some point. We provide guidance. (Volunteer tutors generally have little time for teaching classroom material.)

Please tell us more about your situation. Do you understand what the question is asking? At what point are you stuck?

Have you studied any algebra yet? What class are you taking now? What type of school?

Cheers :cool:

PS: I can see the minus sign in the chart; it's the subscript on s that's hard to read. My guess is that the subscript is n.