Souta wants to compare the mean of his test scores in French class to the mean absolute deviation. Language Test Scores

French Scores

76

62

94

80

He uses the steps below to find both the mean and mean absolute deviation.

French Scores

Step 1
Add the scores.
76 + 62 + 94 + 80 = 312

Step 2
Divide the sum of the scores by 4.
312 divided by 4 = 78

Step 3
Add the differences between the mean and each score.
(76 minus 78) + (62 minus 78) + (94 minus 78) + (80 minus 78) = 0
Step 4 Divide by 4.
StartFraction 0 over 4 EndFraction = 0

In which step did Souta make the first error?
Step 1
Step 2
Step 3
Step 4

the 4th choice is the correct one

step-by-step explanation:

{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