Answer:
0.9988 = 99.88% probability that the mean number of eggs laid would differ from 790 by less than 30.
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 estabilishes 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.
Mean 790 and standard deviation 92.
This means that ![\mu = 790, \sigma = 92](https://tex.z-dn.net/?f=%5Cmu%20%3D%20790%2C%20%5Csigma%20%3D%2092)
Samples of 98
This means that ![n = 98, s = \frac{92}{\sqrt{98}}](https://tex.z-dn.net/?f=n%20%3D%2098%2C%20s%20%3D%20%5Cfrac%7B92%7D%7B%5Csqrt%7B98%7D%7D)
What is the probability that the mean number of eggs laid would differ from 790 by less than 30?
This is the pvalue of Z when X = 790 + 30 = 820 subtracted by the pvalue of Z when X = 790 - 30 = 760. So
X = 820
![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{820 - 790}{\frac{92}{\sqrt{98}}}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7B820%20-%20790%7D%7B%5Cfrac%7B92%7D%7B%5Csqrt%7B98%7D%7D%7D)
![Z = 3.23](https://tex.z-dn.net/?f=Z%20%3D%203.23)
has a pvalue of 0.9994
X = 760
![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{760 - 790}{\frac{92}{\sqrt{98}}}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7B760%20-%20790%7D%7B%5Cfrac%7B92%7D%7B%5Csqrt%7B98%7D%7D%7D)
![Z = -3.23](https://tex.z-dn.net/?f=Z%20%3D%20-3.23)
has a pvalue of 0.0006
0.9994 - 0.0006 = 0.9988
0.9988 = 99.88% probability that the mean number of eggs laid would differ from 790 by less than 30.