Answer:
Step-by-step explanation:
x-y=7
-3x+9y=-39
Divide the second equation by 3
-x +3y = -13
Add this to the first equation
x-y=7
-x +3y = -13
----------------------
0x +2y = -6
Divide by 2
2y/2 = -6/2
y = -3
Now find x
x-y = 7
x -(-3) = 7
x+3 = 7
Subtract 3 from each side
x = 4
(4,-3)
Or by substitution
x-y=7
solve for x
x = 7+y
-3x+9y=-39
Substitute y+7 in for x
-3(7+y) +9y = -39
Distribute
-21 -3y +9y = -39
Combine like terms
-21 +6y = -39
Add 21 to each side
6y = -18
Answer:
The confidence interval is 
Step-by-step explanation:
From the question we are told
The sample proportion 
The margin of error is 
The confidence interval for p is mathematically represented as
=> 
=>
Answer:
You add a bar till the 2 for the 9-10. You add bars till 6 for the 11- 12. You add bars till 8 for the 13-14. You add bars till the 4 for the 15-16.
Step-by-step explanation:
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Add '-1' to each side of the equation.
1 + -1 + 3d = 10 + -1
Combine like terms: 1 + -1 = 0
0 + 3d = 10 + -1
3d = 10 + -1
Combine like terms: 10 + -1 = 9
3d = 9
Divide each side by '3'.
d = 3
Simplifying
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