Answer:
a)
, in which z is related to the confidence level.
b) A sample size of 991 is needed.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of 
, and a confidence level of 
, we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of 
.
The margin of error is:
In 16% of all homes with a stay-at-home parent, the father is the stay-at-home parent
This means that 
a. What sample size is needed if the research firm's goal is to estimate the current proportion of homes with a stay-at-home parent in which the father is the stay-at-home parent with a margin of error of 0.03 (round up to the next whole number).
This is n for which 
. So
, in which z is related to the confidence level.
Question b:
99% confidence level,
So 
, z is the value of Z that has a pvalue of 
, so 
.
Rounding up
A sample size of 991 is needed.
Answer:
260 minutes > 4.25 hours
Step-by-step explanation:
1h=60 min.
0.25 h=¼h=¼*60min=15min.
4.25h=4h+0.25h=60*4+15min=240+15=255min
260>255
Circumference = 2π x radius, so
<span>11 = 2π x radius, from which radius = 11 / 2π </span>
<span>Next, area = π x r^2 = π x (11 / 2π)^2 = 11 / 4π sq inches</span>
19 is the distance between those 2
Answer: Choice C. 107.9 degrees (approximate)
=======================================================
Explanation:
Draw a line segment from A to B. Mark point E as the intersection between this new line segment and the arc CD.
We can see that AE = 4000 because it's another radius of the same circle. The diagram shows that EB = 2800.
So,
AB = AE+EB = 4000+2800 = 6800
Because point D is a tangent point, this means radius AD is perpendicular to tangent segment BD. We have a 90 degree angle at point D, or we can write angle BDA = 90.
With triangle BDA being a right triangle, we can use a trig ratio to compute angle DAB. I'll call this angle A for short.
---------
Apply the cosine ratio. Focus entirely on triangle BDA.
cos(angle) = adjacent/hypotenuse
cos(A) = AD/AB
cos(A) = 4000/6800
cos(A) = 10/17
A = arccos(10/17)
A = 53.9681209275294 ... make sure your calc is in degree mode
A = 53.968
Angle DAB = 53.968 degrees approximately
This represents exactly half of central angle CAD, so we'll double the value to get 2*53.968 = 107.936 which rounds to 107.9 degrees showing why choice C is the answer.
Central angle CAD is exactly equal to the arc it cuts off, minor arc CD. The central angle is roughly 107.9 degrees of a full 360 degree circle, and the same can be said about the outer arc edge piece of minor arc CD.
