Two regional airlines are randomly sampled to compare the pr

Two regional airlines are randomly sampled to compare the proportion of on-time flights. Out of 300 flights, 73% of the flights at Airline A were on time, while Airline B had 82% of 250 flights on time. Find a 95% confidence interval for the difference in the the proportions. find the value for p and perform a 2 sample proportion test. At a = .05, can we conclude there is a difference? How is your answer to this question related to the confidence interval you found? A random sample of seven music majors playing song S counted the number of mistakes each made. Then these musicians practiced a more difficult song. Finally, the same six majors played a song G of equal difficulty to song 5. and the number of mistakes were again tallied. The results are below. At the o = .01 level, is there evidence practicing a more difficult song reduces the number of mistakes? In the 2010 United States census, the four most populous states (CA, TX, NY, FL) had 12.1%), 8.1%. 6.3%, and 6.1% of the total United States population, respectively. Suppose a pollster surveys 1000 US citizens, and 102 are from CA, 84 from TX, 70 from NY, and 70 from FL. At the alpha = .05 level, use a chi^2 test to check whether these four states are properly represented in this survey of 1000 people.

Solution

Sample X N Sample p
1 219 300 0.730000
2 205 250 0.820000

Difference = p (1) - p (2)
Estimate for difference: -0.09
95% CI for difference: (-0.159223, -0.0207769)
Test for difference = 0 (vs not = 0): Z = -2.55 P-Value = 0.011

Fisher\'s exact test: P-Value = 0.014