Here you go hope this helps!
50 POINTS! PLEASE ASAP, BRAINLIST
1 answer:
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Answer:
C. $5180
Step-by-step explanation:
To solve this question, we have to understand the normal probability distribution and the central limit theorem.
Normal probability distribution:
Problems of normally distributed samples can be 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.
Z-scores lower than -2 or higher than 2 are considered unusual.
Central limit theorem:
The Central Limit Theorem estabilishes that, for a random normally distributed 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:
Which of the following mean costs would be considered unusual?
We have to find the z-score for each of them
A. $6350
By the Central Limit Theorem
Not unusual
B. $6180
Not unusual
C. $5180
Unusual, and this is the answer.
Answer:
x = -19 or x = -1
Step-by-step explanation:
We need the quadratic equation in the form
,
so we add 8 to both sides.
Now we have an equation of the form x^2 + ax + b = 0.
We need to factor the quadratic equation. To factor it, we need two numbers, p and q, whose product is b and whose sum is a. Then the factoring is (x + p)(x + q).
In our case, b = 19 and a = 20. We need two numbers that multiply to 19 and add to 20. The numbers are 19 and 1. Our p and q are 19 and 1.
(x + 19)(x + 1) = 0
Since a product of two factors equals zero, either one factor equals zero, or the other factor equals zero. We set each factor equal to zero and solve both equations for x.
x + 19 = 0 or x + 1 = 0
x = -19 or x = -1