Final answer:
The provided statement is false as more information is required to conclude whether the sample is unusual; the population proportion and standard error are needed to calculate the z-score.
Step-by-step explanation:
The statement regarding a sample of 150 young Americans where 20% have delayed starting a family due to economic concerns being considered unusual if the z-score is greater than 2 is a false statement without additional context. To determine the unusualness of a sample proportion, we need the population proportion and the standard error of the sample proportion.
The z-score is calculated as (sample proportion - population proportion) divided by the standard error. Only if the calculated z-score is greater than 2 or less than -2 can we consider the result to be unusual. Without knowing the population proportion and assuming that the sample is a simple random sample, we cannot conclude the given sample is unusual solely based on the percentage provided.