Given parameters:
Quadratic expression:
x² - 6x + 7 = 0
Solve using quadratic formula;
x =
From the equation;
a = 1, b = -6 and c = 7
Input the parameters and solve;
x =
x =
x =
x = or
x = 7 or -1
Answer:
Test scores of 10.2 or lower are significantly low.
Test scores of 31 or higher are significantly high
Step-by-step explanation:
Z-score:
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.
In this problem, we have that:
Significantly low:
Z-scores of -2 or lower
So scores of X when Z = -2 or lower
Test scores of 10.2 or lower are significantly low.
Significantly high:
Z-scores of 2 or higher
So scores of X when Z = 2 or higher
Test scores of 31 or higher are significantly high