Select all the equations that are true when x = 4
1 answer:
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<h3>Answer: (-infinity, 7]</h3>
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Explanation:
The first interval (-infinity, 3) describes any number less than 3, so we can write x < 3 in short hand (where x is the unknown number).
The second interval (-1, 7] means we start at -1 and stop at 7. We do not include -1 but include 7. So we say that (ie x is between -1 and 7; exclude -1, include 7)
If you were to graph each ona number line, you would see that the too intervals have overlapping parts. The right most edge extends out as far as x = 7. There is no left most edge as it goes onforever that direction.
Therefore, the to intervals combine to get which turns into the interval notation answer of (-infinity, 7]
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It might help to think of it like this: x < 3 and say "x is some number that is less than 3, or it is between -1 and 7". So x could be anything less than 7, including 7 itself.
Answer:
B) 0.0069
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 question, we have that:
Find the probability that their mean rebuild time exceeds 9.1 hours.
This is 1 subtracted by the pvalue of Z when X = 9.1. So
By the Central Limit Theorem
has a pvalue of 0.9931
1 - 0.9931 = 0.0069
So the answer is B.