Answer:
A.one sample z-confidence interval for the population proportion
Step-by-step explanation:
-A confidence interval is a range of values in which the true population mean is believed to lie.
-Given just one sample, the one sample z-confidence interval for the population proportion is appropriate and is defined as:

Answer:

Step-by-step explanation:
Given

Required
Simplify
To do this, we apply distributive property;


Hence, the simplified form is 
35 but dubble check to be sure
Answer: the surplus is 12$
Step-by-step explanation:
You only need to calculate what you bought it for and what you sold it for
You bought the materials for eight dollars and sold the materials/bracelet for 20, 20-8 means you have a surplus of 12 dollars