Answer:
B, using a sample of size 200
Step-by-step explanation:
just got it right
Answer: A. 664
Step-by-step explanation:
Given : A marketing firm is asked to estimate the percent of existing customers who would purchase a "digital upgrade" to their basic cable TV service.
But there is no information regarding the population proportion is mentioned.
Formula to find the samples size , if the prior estimate to the population proportion is unknown :
![n=0.25(\dfrac{z*}{E})^2](https://tex.z-dn.net/?f=n%3D0.25%28%5Cdfrac%7Bz%2A%7D%7BE%7D%29%5E2)
, where E = Margin of error.
z* = Two -tailed critical z-value
We know that critical value for 99% confidence interval =
[By z-table]
Margin of error = 0.05
Then, the minimum sample size would become :
![n=0.25(\dfrac{2.576}{0.05})^2](https://tex.z-dn.net/?f=n%3D0.25%28%5Cdfrac%7B2.576%7D%7B0.05%7D%29%5E2)
Simplify,
![n=0.25\times2654.3104=663.5776\approx664](https://tex.z-dn.net/?f=n%3D0.25%5Ctimes2654.3104%3D663.5776%5Capprox664)
Thus, the required sample size= 664
Hence, the correct answer is A. 664.
Equations:
Let x=the larger number
1. y=x-3
2. y=1/3(x+9)
4x + 2y <= 30
ignore this text need to reach char minimum
11% of 80 is 0.11*80=8.8
80-8.8=71.2
Answer B