Write the equation of a parabola with vertex (2,-1) and directrix y=-3
1 answer:
Answer:
Step-by-step explanation:
a parabola is the graph of a quadratic equation, so the general equation is
If the directrix is negative, it means the graph opens down, so a is -
and c is -3
this gives us
all we need now is what is b
b is the y intercept for
to find the y intercept, we plug in 0 for x
so the y intercept is -3
so the equation is
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Answer:
Let X the random variable that represent the number of children per fammili of a population, and for this case we know the following info:
Where and
We select a sample of n =64 >30 and we can apply the central limit theorem. From the central limit theorem we know that the distribution for the sample mean is given by:
And for this case the standard error would be:
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 number of children per fammili of a population, and for this case we know the following info:
Where and
We select a sample of n =64 >30 and we can apply the central limit theorem. From the central limit theorem we know that the distribution for the sample mean is given by:
And for this case the standard error would be: