Answer:
0.0409 = 4.09% probability that the mean height of the 35 NBA players will be more than 80 inches.
Step-by-step explanation:
To solve this question, we need to understand the normal probability distribution and the central limit theorem.
Normal Probability Distribution
Problems of normal distributions can be solved using the z-score formula.
In a set with mean
and standard deviation
, the z-score of a measure X is given by:
![Z = \frac{X - \mu}{\sigma}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7BX%20-%20%5Cmu%7D%7B%5Csigma%7D)
The Z-score 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. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.
Central Limit Theorem
The Central Limit Theorem establishes that, for a normally distributed random variable X, with mean
and standard deviation
, the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean
and standard deviation
.
For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.
The average height of a current NBA player is 79 inches with a standard deviation of 3.4 inches.
This means that ![\mu = 79, \sigma = 3.4](https://tex.z-dn.net/?f=%5Cmu%20%3D%2079%2C%20%5Csigma%20%3D%203.4)
A random sample of 35 current NBA players is taken.
This means that ![n = 35, s = \frac{3.4}{\sqrt{35}}](https://tex.z-dn.net/?f=n%20%3D%2035%2C%20s%20%3D%20%5Cfrac%7B3.4%7D%7B%5Csqrt%7B35%7D%7D)
What is the probability that the mean height of the 35 NBA players will be more than 80 inches?
This is 1 subtracted by the p-value of Z when X = 80. So
![Z = \frac{X - \mu}{\sigma}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7BX%20-%20%5Cmu%7D%7B%5Csigma%7D)
By the Central Limit Theorem
![Z = \frac{X - \mu}{s}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7BX%20-%20%5Cmu%7D%7Bs%7D)
![Z = \frac{80 - 79}{\frac{3.4}{\sqrt{35}}}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7B80%20-%2079%7D%7B%5Cfrac%7B3.4%7D%7B%5Csqrt%7B35%7D%7D%7D)
![Z = 1.74](https://tex.z-dn.net/?f=Z%20%3D%201.74)
has a p-value of 0.9591
1 - 0.9591 = 0.0409
0.0409 = 4.09% probability that the mean height of the 35 NBA players will be more than 80 inches.