here,
2x-6y= -12
2(x-3y)= -12
x-3y = -6...........eq1
x+2y=14............eq2
we can subtract the above two given equations
we get,
___________
so,
y=4
now to find the value of x we have to substitute the value of y in any of the above two equations, I choose eq2
we get,
Answer:
Step-by-step explanation:
Hello, please consider the following.
Hope this helps.
Do not hesitate if you need further explanation.
Thank you
Answer:
2.28% of tests has scores over 90.
Step-by-step explanation:
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.
In this problem, we have that:
What proportion of tests has scores over 90?
This proportion is 1 subtracted by the pvalue of Z when X = 90. So
has a pvalue of 0.9772.
So 1-0.9772 = 0.0228 = 2.28% of tests has scores over 90.
