What is the result when the number 40 is decreased by 10%?
1 answer:
You might be interested in
According to Vieta's Formulas, if 
are solutions of a given quadratic equation:
Then:
is the completely factored form of 
.
If choose
, then:
So, according to Vieta's formula, we can get:
But:
![d^4-8d^2+16=(d^2-4)^2=[(d+2)(d-2)]^2=(d+2)^2(d-2)^2](https://tex.z-dn.net/?f=d%5E4-8d%5E2%2B16%3D%28d%5E2-4%29%5E2%3D%5B%28d%2B2%29%28d-2%29%5D%5E2%3D%28d%2B2%29%5E2%28d-2%29%5E2)
Then:
If choose
So, according to Vieta's formula, we can get:
But
Answer:
Keenan's z-score was of 0.61.
Rachel's z-score was of 0.81.
Step-by-step explanation:
Z-score:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean and standard deviation
, the z-score 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 p-value, we get the probability that the value of the measure is greater than X.
Keenan scored 80 points on an exam that had a mean score of 77 points and a standard deviation of 4.9 points.
This means that
So
Keenan's z-score was of 0.61.
Rachel scored 78 points on an exam that had a mean score of 75 points and a standard deviation of 3.7 points.
This means that . So
Rachel's z-score was of 0.81.