Hey guys, I'm relearning some Algebra and was confused about this problem. In the equation, the problem was divided by 3. This m
akes sense because its easier to work with smaller numbers. However, after that the negative signs swapped. Why does this happen? I remember switching signs years ago when I learned it but now I can't remember the rule as to why. Thank you so much.
2 answers:
You might be interested in
Answer:
1) the planning value for the population standard deviation is 10,000
2)
a) Margin of error E = 500, n = 1536.64 ≈ 1537
b) Margin of error E = 200, n = 9604
c) Margin of error E = 100, n = 38416
3)
As we can see, sample size corresponding to margin of error of $100 is too large and may not be feasible.
Hence, I will not recommend trying to obtain the $100 margin of error in the present case.
Step-by-step explanation:
Given the data in the question;
1) Planning Value for the population standard deviation will be;
⇒ ( 50,000 - 10,000 ) / 4
= 40,000 / 4
σ = 10,000
Hence, the planning value for the population standard deviation is 10,000
2) how large a sample should be taken if the desired margin of error is;
we know that, n = [ ( × σ ) / E ]²
given that confidence level = 95%, so = 1.96
Now,
a) Margin of error E = 500
n = [ ( × σ ) / E ]²
n = [ ( 1.96 × 10000 ) / 500 ]²
n = [ 19600 / 500 ]²
n = 1536.64 ≈ 1537
b) Margin of error E = 200
n = [ ( × σ ) / E ]²
n = [ ( 1.96 × 10000 ) / 200 ]²
n = [ 19600 / 200 ]²
n = 9604
c) Margin of error E = 100
n = [ ( × σ ) / E ]²
n = [ ( 1.96 × 10000 ) / 100 ]²
n = [ 19600 / 100 ]²
n = 38416
3) Would you recommend trying to obtain the $100 margin of error?
As we can see, sample size corresponding to margin of error of $100 is too large and may not be feasible.
Hence, I will not recommend trying to obtain the $100 margin of error in the present case.
(side note: your formula C = 2πr^2 is incorrect, it should be C = 2πr)
Answer:
r = 9
Step-by-step explanation:
First let's find the circumference of Circle A. To use the formula we need radius. Since we have a diameter just divide by 2 to get radius. 27 / 2 = 13.5
Now plug that into C = 2πr: 2π*(13.5) = 27π
The question says that the area of circle B is 3x this value, so Circle B's area must be: 27π * 3 = 81π
Now plug that into A = πr^2 and solve for r:
(edited to correct a brain fart)