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.
R = 16 according to the problem, so the total amount of income will be:
$20*16 + $15*(40 - 16)
= $320 + <span>$15*(24)
= </span>$320 + <span>$360
= $680
that is the income, but the expenses are $275 so the total revenue is the subtraction of those two
total revenue = $680 - $275
= $405</span>
13 - (x+2) = 8
subtract 13 from both sides
-(x+2) = -5
divide by -1 to get rid of negative
(x+2) = 5
subtract 2 from both sides
x=3
Answer:
I cant see it
Step-by-step explanation:
I dont Know