Please explain why you choose these answers. Thanks! 1. A simple random sample o
ID: 3043507 • Letter: P
Question
Please explain why you choose these answers. Thanks!
1. A simple random sample of 100 athletes is selected from a large high school. In the sample, there are 15 football players. What is the standard error of the sample proportion of football players? A) 0.00128 B) 0.0357 C) 0.05 D) 0.357 2. A simple random sample of 450 residents in the state of New York is taken to estimate the proportion of people who live within 1 mile of a hazardous waste site. If 135 of the residents in the sample live within 1 mile of a hazardous waste site, what are the values of the sample proportion of people who live within 1 mile of a hazardous waste site and its standard error? A) 0.3 and 0.01 B) 0.3 and 0.022 C) 0.3 and 0.21 D) 0.7 and 0.022 noted psychic was tested for extrasensory perception. The psychic was presented with 200 cards face down and asked to determine if each card were one of five symbols: a star, a cross, a circle, a square, or three wavy lines. The psychic was correct in 50 cases. Let p represent the probability that the psychic correctly identifies the symbol on the card in a random trial. Assume the 200 trials can be treated as a simple random sample from the population of all guesses the psychic would make in his lifetime. Based on the results of the test, what is a 95% confidence interval for p? A) 0.25±0.004 B) 0.25±0.05 C) 0.25±0.055 D) 0.25 ± 0.060 3. A
Explanation / Answer
1. n=100 = total number of observations
p=sample proportion = 15/100 = 3/20
standard error of sample proportion:
SEp = sqrt [ p(1 - p) / n ] = sqrt [ {(3/20) (17/20) } / 100 ] = 0.03570714
2. number of observation=n=450
no. of people who live within 1 mile is =135
sample proportion = p = 135/450 = 0.3
standard error = sqrt[p(1-p)/n]
=sqrt [ (0.3*0.7)/450] = 0.02160247 = (rounding off) 0.022
answer is option (B)
10. a 99% confidence interval is wider than 80% confidence interval. this is true.