A company hopes to improve its engines,setting a goal of no more than 3% of customers using their warranty on defective engine parts.A random survey of 1200 customers found only 20 with complaints.Create a 95% confidence interval for the true level of warranty users among all customers.
A)Based on the data,we are 95% confident the proportion of warranty users is between 0% and 2.4%.Therefore,the company has met its goal.
B)Based on the data,we are 95% confident the proportion of warranty users is between 1% and 3%.Therefore,the company has met its goal.
C)Based on the data,we are 95% confident the proportion of warranty users is between 0.9% and 3.8%.Therefore,the company has not met its goal.
D)Based on the data,we are 95% confident the proportion of warranty users is between 2.0% and 2.4%.Therefore,the company has met its goal.
E)Based on the data,we are 95% confident the proportion of warranty users is between 0.9% and 2.4%.Therefore,the company has met its goal.

Question

Quizplus · Accepted Answer

The sample proportion is 20/1200 = 0.0167. Using the formula for a confidence interval for a proportion, the 95% confidence interval is approximately 0.9% to 2.4%, which is below the 3% goal.

A Company Hopes to Improve Its Engines,setting a Goal of No