the vertex of a quadratic function is (6,2) and the y-intercept of the function is (0,-70). the equation of the function in vert
2 answers:
Answer:
The value of a is -2
Step-by-step explanation:
In the equation of the quadratic function:
The point (h,k) is the vertex and all the points with the form (x,f(x)) belong to the quadratic functions.
Then, in this case, the point (6,2) is the vertex (h,k) and the y-intercept of the function (0,-70) is a point that follow the form (x,f(x)).
So, if we replace, h by 6, k by 2, x by 0 and f(x) by -70 and we solve for a, we get:
Therefore the value of a on the equation is -2.
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Answer:
0.8926 = 89.26% probability that the mean weight of the sample of horses would differ from the population mean by less than 15lbs if 31 horses are sampled at random from the stable
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 normally distributed samples are solved using the z-score formula.
In a set with mean and standard deviation
, the zscore of a measure X is given by:
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.
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.
In this problem, we have that:
What is the probability that the mean weight of the sample of horses would differ from the population mean by less than 15lbs if 31 horses are sampled at random from the stable?
pvalue of Z when X = 975 + 15 = 990 subtracted by the pvalue of Z when X = 975 - 15 = 960. So
X = 990
By the Central Limit Theorem
has a pvalue of 0.9463
X = 960
has a pvalue of 0.0537
0.9463 - 0.0537 = 0.8926
0.8926 = 89.26% probability that the mean weight of the sample of horses would differ from the population mean by less than 15lbs if 31 horses are sampled at random from the stable