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.
Answer:
50 and 10
Step-by-step explanation:
x+4x+10=y
y is 60
x+4x+10=60
5x+10=60
5x=50
x=10
or
10*4=40
40+10=50
50+10=60
It will automatically be over 1
Answer:
Step-by-step explanation:
You would do this question like this.
4 meats * 2 cheeses * x breads = 24 different kinds of sandwiches.
8x = 24
8x/8 = 24/8
x = 3
There are 3 different kinds of breads.