You want to design a survey to determine how much money people are willing to spend on concert tickets. Which of the following methods would be most practical and have
the least bias?
Choose 4 neighborhoods at random and poll every home in those
neighborhoods.
Poll 10% of the homes in the area chosen at random.
Poll the first 100 people who enter the mall.
Poll everyone in the area.

The correct option is;

Choosing 4 neighborhoods at random and poll every home in those neighborhoods

Step-by-step explanation:

Given that the survey relate to how much money people are willing to spend on on concert tickets with the goal of being practical and unbiased, we have;

Required sampling = Random Sampling

The preferable type of random sampling is either;

1) Simple random sampling

Sampling a given percentage of the homes in the area randomly

2) Clustered random sampling

Completely polling entire population of randomly selected area

Given the practicability of sampling concert goers, since people may have different interests, a better representative sample will be to perform the clustered random sampling approach by choosing 4 neighborhoods at random and poll every home in those neighborhoods.

yes because there is exactly one y value for every x value

for function there can't be more than one value for every x value