Answer:
y = 6.5
Step-by-step explanation:
Using a ratio
10 13
----- = -----------
10+5 13+y
10 13
----- = -----------
15 13+y
Using cross products
10(13+y) = 13*15
10(13+y) = 195
130+10y = 195
Subtract 130 from each side
10y = 65
Divide by 10
y = 65/10
y = 6.5
Answer:
145
.8x = 116 (80% of class is 116)
x=145
Step-by-step explanation:
Answer:
The lower bound for a 90% confidence interval for the percentage of all American adults who believe in ghosts is 0.3549
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
.
For this problem, we have that:

90% confidence level
So
, z is the value of Z that has a pvalue of
, so
.
The lower limit of this interval is:

The lower bound for a 90% confidence interval for the percentage of all American adults who believe in ghosts is 0.3549
B since a circle is all the points equidistant to a given point called the center of the circle.