Hayden wants to find out what grade he must receive on his next math test in order to receive a 90 on his report card. His current math test grades are a 90, 89, 91, and 92. Which measure of center would be best for him to use

Mean

Step-by-step explanation:

Mean is best used when the numbers in the data set are close together and the number of outliers are limited because outliers will either increase or decrease the mean such that it would not be a true representation of the data set.

In cases like the above however where the numbers are generally in the same range, the mean would provide a center measure that is the most representative because it would simply be a simple average of the numbers.

b

step-by-step explanation:

the word superfluous means unnecessary

{x = -1/2 ,   y = -1

step-by-step explanation:

solve the following system:

{2 x + y = -2

{10 x - 3 y = -2

in the first equation, look to solve for y:

{2 x + y = -2

{10 x - 3 y = -2

subtract 2 x from both sides:

{y = -2 x - 2

{10 x - 3 y = -2

substitute y = -2 x - 2 into the second equation:

{y = -2 x - 2

{10 x - 3 (-2 x - 2) = -2

10 x - 3 (-2 x - 2) = (6 x + 6) + 10 x = 16 x + 6:

{y = -2 x - 2

{16 x + 6 = -2

in the second equation, look to solve for x:

{y = -2 x - 2

{16 x + 6 = -2

subtract 6 from both sides:

{y = -2 x - 2

{16 x = -8

divide both sides by 16:

{y = -2 x - 2

{x = -1/2

substitute x = -1/2 into the first equation:

{y = -1

{x = -1/2

collect results in alphabetical order:

answer:   {x = -1/2 ,   y = -1