Given:
Sample proportion = 85% = 0.85.
Confidence level (CL) = 90%.
Confidence interval (CI)
![\hat{p} \pm z^{*} \sqrt{ \frac{\hat{p}(1-\hat{p})}{n} } \\ where \\ n=sample\, size \\ z^{*}=1.645 \, at \, 90\% \, CL](https://tex.z-dn.net/?f=%5Chat%7Bp%7D%20%5Cpm%20z%5E%7B%2A%7D%20%5Csqrt%7B%20%5Cfrac%7B%5Chat%7Bp%7D%281-%5Chat%7Bp%7D%29%7D%7Bn%7D%20%7D%20%20%5C%5C%20where%20%5C%5C%20n%3Dsample%5C%2C%20size%20%5C%5C%20z%5E%7B%2A%7D%3D1.645%20%5C%2C%20at%20%5C%2C%2090%5C%25%20%5C%2C%20CL)
We want the confidence interval to be 5% or 0.05. Therefore
![0.85 - 1.645 \sqrt{ \frac{0.85(1-0.85)}{n} }=0.05 \\ 0.85 - \frac{0.5874}{ \sqrt{n} } =0.05 \\ \frac{0.5874}{ \sqrt{n} }=0.8 \\ \sqrt{n} = .7342 \\ n=0.54](https://tex.z-dn.net/?f=0.85%20-%201.645%20%5Csqrt%7B%20%5Cfrac%7B0.85%281-0.85%29%7D%7Bn%7D%20%7D%3D0.05%20%5C%5C%200.85%20-%20%20%5Cfrac%7B0.5874%7D%7B%20%5Csqrt%7Bn%7D%20%7D%20%3D0.05%20%5C%5C%20%20%5Cfrac%7B0.5874%7D%7B%20%5Csqrt%7Bn%7D%20%7D%3D0.8%20%5C%5C%20%20%5Csqrt%7Bn%7D%20%3D%20.7342%20%5C%5C%20n%3D0.54)
Because this number is less than 1, a default sample size of 30 (for the normal distribution) is recommended.
Answer: 30
Answer:
0.375
Step-by-step explanation:
Just divide 3 over 8.
With constant speed it will take her : 405 ml / 45= 9 hours of drive
10 million dollars year 1
13 million dollars year 2
26 million dollars year 3
Answer:
x=-2.5,9
Step-by-step explanation:
Set them equal to each other to say 2x^2-9x=4x+45. Get them all on one side to get 2x^2-13x-45. Factor that out to get (x+2.5)(x-9). Set that equal to 0 to get x=-2.5,9