Use the Normal to model the distribution of sample proportions.
-It is generally believed that electrical problems affect about 14% of new cars. An
Automobile mechanic conducts diagnostic tests on 128 new cars on the lot. What is the
Probability that in this group between 10% and 18% of the new cars will be found to have
Electrical problems?
A) 0.0985
B) 0.197
C) 0.9015
D) 0.803
E) 0.500

Question

Quizplus · Accepted Answer

The sample proportion follows a normal distribution with mean 0.14 and standard deviation sqrt((0.14*0.86)/128). Using the normal approximation, the probability that the sample proportion is between 0.10 and 0.18 is approximately 0.803.

Use the Normal to Model the Distribution of Sample Proportions