Answer: a) Required minimum sample size= 219
b) Required minimum sample size= 271
Step-by-step explanation:
As per given , we have
Margin of error : E= 5% =0.05
Critical z-value for 90% confidence interval : 
a) Prior estimate of true proportion: p=28%=0.28
Formula to find the sample size :-

Required minimum sample size= 219
b) If no estimate of true proportion is given , then we assume p= 0.5
Formula to find the sample size :-

Required minimum sample size= 271
Answer: X = -9
Step-by-step explanation:
You can set up a ratio to solve this.
208/13 = -144/x
208x=-1872
x = -9
Answer:
or 
Step-by-step explanation:
You need to complete the square before you can take the square root of both sides.

Subtract 10 from both sides.

To complete the square, you need to add the square of half of the x-term coefficient to both sides.
The x-term coefficient is 7. Half of that is 7/2. Square it to get 49/4. Now we add 49/4 to both sides of the equation.



Now we use the square root property, if
, then



or
or 
or 
Let x= original number
equation: 2x+24=2/7 x
move 2x over to the other side of the equation to get 24=-12/7 x. Then, multiply both sides of the equation by -7/12 to isolate the variable.
The final answer should be x=-14