Westonci.ca connects you with experts who provide insightful answers to your questions. Join us today and start learning! Join our Q&A platform and connect with professionals ready to provide precise answers to your questions in various areas. Get detailed and accurate answers to your questions from a dedicated community of experts on our Q&A platform.

A large car dealership claims that 47% of its customers are looking to buy a sport utility vehicle (SUV). A random sample of 61 customers is surveyed. What is the probability that less than 40% of the sample are looking to buy an SUV?

Sagot :

Using the normal distribution and the central limit theorem, it is found that the probability is of 0.1368 = 13.68%.

Normal Probability Distribution

In a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the z-score of a measure X is given by:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

  • It measures how many standard deviations the measure is from the mean.
  • After finding the z-score, we look at the z-score table and find the p-value associated with this z-score, which is the percentile of X.
  • By the Central Limit Theorem, for a proportion p in a sample of size n, the sampling distribution of sample proportion is approximately normal with mean [tex]\mu = p[/tex] and standard deviation [tex]s = \sqrt{\frac{p(1 - p)}{n}}[/tex], as long as [tex]np \geq 10[/tex] and [tex]n(1 - p) \geq 10[/tex].

In this problem:

  • 47% of its customers are looking to buy a sport utility vehicle (SUV), hence p = 0.47.
  • A sample of 61 customers is taken, hence n = 61.

The mean and the standard error are given by:

[tex]\mu = p = 0.47[/tex]

[tex]s = \sqrt{\frac{p(1 - p)}{n}} = \sqrt{\frac{0.47(0.53)}{61}} = 0.0639[/tex]

The probability that less than 40% of the sample are looking to buy an SUV is the p-value of Z when X = 0.4, hence:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

By the Central Limit Theorem

[tex]Z = \frac{X - \mu}{s}[/tex]

[tex]Z = \frac{0.4 - 0.47}{0.0639}[/tex]

Z = -1.095

Z = -1.095 has a p-value of 0.1368.

0.1368 = 13.68% probability that less than 40% of the sample are looking to buy an SUV.

To learn more about the normal distribution and the central limit theorem, you can check https://brainly.com/question/24663213