solve the system of equations 3y 2z = 12 and y – z = 9. a. y = 24, z = 15 b. y = 6, z = 15 c. y = 6, z = –3 d. y = –6, z = 15
1 answer:
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Answer:
a)
e.none of the above
b)
a.0.0200
c)
a.0.0668
d)
c.0.6853
Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
The central limit theorem states that "if we have a population with mean μ and standard deviation σ and take sufficiently large random samples from the population with replacement, then the distribution of the sample means will be approximately normally distributed. This will hold true regardless of whether the source population is normal or skewed, provided the sample size is sufficiently large".
Solution to the problem
Let X the random variable that represent the weights of a population, and for this case we know the distribution for X is given by:
Where and
From the central limit theorem we know that the distribution for the sample mean is given by:
Part a
Part b
Part c
We want this probability:
For this case we can use the z score formula given by:
And using this formula we got:
Part d
We want this probability:
For this case we can use the z score formula given by:
And using this formula we got: