Answer:
12
Step-by-step explanation:
i done the butterfly method
Step-by-step explanation:
hey can I have this question in English write can totally ask your question I don't think that I am doing this for purposes please ask this question and English so I can ask this question please ask this question in English if you I am from India so I don't know this all languages Thank you
Answer:
A score of 150.25 is necessary to reach the 75th percentile.
Step-by-step explanation:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean
and standard deviation
, the zscore 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 pvalue, we get the probability that the value of the measure is greater than X.
A set of test scores is normally distributed with a mean of 130 and a standard deviation of 30.
This means that ![\mu = 130, \sigma = 30](https://tex.z-dn.net/?f=%5Cmu%20%3D%20130%2C%20%5Csigma%20%3D%2030)
What score is necessary to reach the 75th percentile?
This is X when Z has a pvalue of 0.75, so X when Z = 0.675.
![Z = \frac{X - \mu}{\sigma}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7BX%20-%20%5Cmu%7D%7B%5Csigma%7D)
![0.675 = \frac{X - 130}{30}](https://tex.z-dn.net/?f=0.675%20%3D%20%5Cfrac%7BX%20-%20130%7D%7B30%7D)
![X - 130 = 0.675*30](https://tex.z-dn.net/?f=X%20-%20130%20%3D%200.675%2A30)
![X = 150.25](https://tex.z-dn.net/?f=X%20%3D%20150.25)
A score of 150.25 is necessary to reach the 75th percentile.
Answer:
21
Step-by-step explanation: