Answer:
Z=-2
This value means that the score of Rachel 550 it's 2 deviations below the mean of the population 
Step-by-step explanation:
1) Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
represent the population mean for the Graduate Record Exam (GRE)
represent the population standard deviation for Graduate Record Exam (GRE)
2) Solution to the problem
Let X the random variable that represent the Graduate Record Exam (GRE) of a population, and for this case we know the distribution for X is given by:
Where and
We want to find the z score for a score of 550. And in order to do this we need to apply the formula for the z score given by:
If we apply this formula to our probability we got this:
So the answer for our case would be Z=-2
This value means that the score of Rachel 550 it's 2 deviations below the mean of the population
Answer:
Option D is correct.
and 
Step-by-step explanation:
Floor function states that the greatest integer that is less than or equal to x.
It is represented by: 
Ceiling function states that the least integer that is greater than or equal to x.
It is represented by: 
As per the statement:-
Kareem wrote the values show below:
, 
, 
and .
by definition:
= 4
= 2
=3
= 4
From the given options only pair which is equivalent is:
and
Answer: She will pay $52.68, including taxes
Step-by-step explanation: One can of tennis ball is $4 and there are no discount on it. Elena bought 3 cans, so:
can = 3 x 4 = 12
One tennis racket is $43 but it has a discount of 15%:
discount = 0.15 x 43 = 6.45
total racket = 43 - 6.45 = 36.55
Elena will have to pay:
pay = 12 + 36.55 = 48.55
She will also have to pay taxes, which are 8.5% over the price she paid:
pay + tax = 48.55 x 0.085 = 4.13
total to pay = 48.55 + 4.13 = 52.68
Buying 3 can of tennins ball and one racket, Elena paid $52.68, including taxes.
