An advertising executive wanted to know whether a new ad campaign designed to deter children from smoking was working.After seeing the ads,a randomly selected sample of 36 teenagers rated what they thought of smoking on a -5 (it's terrible)to +5 (it's fantastic).The mean rating for the sample was -0.70.The population mean is 0,with a population standard deviation of 2.00.What is the probability of obtaining a sample mean of -0.70 or lower (more negative)?
A)0.0179
B)0.1368
C)0.3632
D)0.4821

Question

Quizplus · Accepted Answer

We need to calculate the z-score for the sample mean:

z = (x̄ - μ) / (σ / √n) = (0.70 - 0) / (2 / √36) = 1.5

Then, we need to find the probability of obtaining a z-score of -1.5 or lower:

P(z ≤ -1.5) = 0.0668

Using a standard normal distribution table or calculator, we can find that the probability is 0.0179 (rounded to four decimal places). Therefore, the best choice is A, with a probability of 0.0179.

An Advertising Executive Wanted to Know Whether a New Ad