The Coca-Cola Company has 40% of the cola market.The probability that a sample proportion for n = 30 falls within 0.10 of the true population proportion of 0.40,which represents the proportion of cola drinkers who prefer a Coca-Cola drink is:
A) 0.7372.
B) 0.3686.
C) 0.4599.
D) 0.9198.
E) not enough information given to make calculation.

Question

Quizplus · Accepted Answer

The calculation can be done using the formula for the standard error of a proportion and the normal distribution. The standard error of the proportion is sqrt[p(1-p)/n], where p = 0.40 and n = 30. Then, using the normal distribution, we find the probability that the sample proportion falls within 0.10 of the true proportion. The correct calculation leads to the probability of 0.7372, making choice A correct.

The Coca-Cola Company Has 40% of the Cola Market