Answer:
$253
Step-by-step explanation:
Margin of error is the critical value times the standard error.
MoE = z × σ/√n
At 99% confidence, z = 2.576.
MoE = 2.576 × 844/√74
MoE = 253
Answer:
cos − 1 ( x ) [ − 1 , 1 ] [ 0 , π ]
Answer:
<em>a) x = -2+√3 and -2-√3</em>
<em>b) x = -1 + 2√3/3 and -1 - 2√3/3</em>
<em>c) x = 3.185 and 0.315</em>
Step-by-step explanation:
To solve the following quadratic equation, we will use the general formula
x = -b±√b²-4ac/2a
a) x²+4x+1 = 0
a = 1, b = 4 and c = 1
Substitute into the formula
x = -4±√4²-4(1)(1)/2(1)
x = -4±√16-4/2
x = -4±√12/2
x = -4±2√3/2
x = (-4+2√3)/2 and (-4-2√3)/2
<em>x = -2+√3 and -2-√3</em>
b) 3x²+6x-1 = 0
a = 3, b = 6 and c = -1
Substitute into the formula
x = -6±√6²-4(3)(-1)/2(3)
x = -6±√36+12/6
x = -6±√48/6
x = -6±4√3/6
x = (-6+4√3)/6 and (-6-4√3)/6
<em>x = -1 + 2√3/3 and -1 - 2√3/3</em>
<em></em>
c) 2x² - 7x + 2 = 0
a = 2, b = -7 and c = 2
x = -(-7)±√(-7)²-4(2)(2)/2(2)
x = 7±√49-16/4
x =7±√33/4
x = 7±5.74/4
x = 7+5.74/4 and 7-5.74/4
x = 12.74/4 and 1.26/4
<em>x = 3.185 and 0.315</em>
<em></em>
The answer for question four is B.80
