An insurance company states that 90% of its claimssettled within 30 days. A consumer group selected a random sample of75 of the company's claims to test this statement. If theconsumer group found that 55 of the claims were settled within 30days, do they have sufficient reason to support their contention thatfewer than calculate the p-value and use it for drawing theconclusion. What is the population of interest in thisproblem? Find the 95% confidence interval for the populationproportion.
Explanation / Answer
H0: p_actual = p = .9 Ha: p_actual does not equal p p_actual = 55/75 = .733 z = (p_actual - p) / sqrt(p * (1-p)/n) = (.733 - .9) / sqrt(.9 * .1/ 75) = -4.82 --> p is EXTREMELY small (