Answer:

Step-by-step explanation:
The firm tests 75 parts, and finds that 0.25 of them are notusable
n = 75
x = 0.25 \times 75 = 18.75≈19



Confidence level = 95%
So, Z_\alpha at 95% = 1.96
Formula of confidence interval of one sample proportion:


Confidence interval 
Answer:
Step-by-step explanation:
x+y=12
x-y=18
Now eliminate the y by adding the two equations together to get
2x=30
x=15
then solve for y.
15+y=12
15-y=18
y= -3
The answer is 50 y squared minus 4 x squared
Answer:
24 ft
Step-by-step explanation:
a^2 + b^2 = c^2
7^2 + b^2 = 25^2
7^2 - 25^2 = -b^2
49 - 625 = -b^2
-576 = -b^2
24 = b