(2x^3-4x^2-3x-9) ÷ x-3
1 answer:
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Answer:
The interval containing the middle-most 48% of sample means is between 218.59 to 221.41.
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 distributied random variable X, with mean and standard deviation
, the sample means with size n can be approximated to a normal distribution with mean
and standard deviation
In this problem, we have that:
Find the interval containing the middle-most 48% of sample means:
50 - 48/2 = 26th percentile to 50 + 48/2 = 74th percentile. So
74th percentile
value of X when Z has a pvalue of 0.74. So X when Z = 0.643.
By the Central Limit Theorem
26th percentile
Value of X when Z has a pvalue of 0.26. So X when Z = -0.643
The interval containing the middle-most 48% of sample means is between 218.59 to 221.41.
9514 1404 393
Answer:
x = 1 or 5
Step-by-step explanation:
The notion of "cross-multiplying" is the idea that the numerator on the left is multiplied by the denominator on the right, and the numerator on the right is multiplied by the denominator on the left. This looks like ...
Then the solution proceeds by eliminating parentheses, and solving the resulting quadratic equation.
_____
<em>Comment on "cross multiply"</em>
Like a lot of instructions in Algebra courses, the idea of "cross multiply" describes <em>what the result looks like</em>. It doesn't adequately describe how you get there. The <em>one and only rule</em> in solving Algebra problems is "<em>whatever is done to one side of the equation must also be done to the other side of the equation</em>." If you multiply one side by one thing and the other side by a different thing, you are violating this rule.
What looks like "cross multiply" is really "<em>multiply by the product of the denominators</em> and cancel like terms from numerator and denominator." Here's what that looks like with the intermediate steps added.