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 
Our answer would be 134.6
Answer
x1 = −1.768
Step-by-step explanation:
Answer:
k=10
Step-by-step explanation:
4k + 12= 52
minus 12 on both sides
4k=40
now divide by 4
k=10
1/4+5/4=1.5
1.5 divided by 4 = 0.5625