Question

1. a survey of 2000 randomly selected musician found that 304 of them are left-handed. The 92% confidence interval for the true proportion of all musicians that are left-handed is (0.139, 0.165).

What is the best conclusion to draw from this interval?

1. There is a 90% chance that between 13.9% and 16.5% of any sample of musicians will be left-handed
2. We can be 90% confident that the constructed confidence interval captures the unknown population proportion of musicians that are left-handed
3. We cannot make any meaningful conclusions because only one sample from the population was used
4. We can be 90% confident that fewer than 20% of musicians are left-handed

2. The use of random sampling helps prevent which type of bias?

1. The user of an estimator that is bias
2. Measurement bias
3. Sampling bias
4. Confounding bias

Answer 1

the calculated 92% confidence interval for the true proportion is is (0.139, 0.165)

so the interpretation as follows:

it can be said that the we are 92% confident that the true proportion of all musicians that are left handed is between 0.139 and 0.165 in the population.

so correct answer is

B: We can be 90% confident that the constructed confidence interval captures the unknown population proportion of musicians that are left-handed.

2)

random sampling is used to avoid the sampling bias, in this samples are choosed randomly by chance.

so correct answer is

C: sampling bias