PLEASE HELP! - The scatterplot below shows the number of weeks that students have been in keyboarding class and the number of mi
stakes that they made on a keyboarding test.
(Graph Below)
Which statement about the scatterplot is true?
A. As the number of weeks in class increases, the number of keyboarding mistakes decreases.
B. As the number of weeks in class increases, the number of keyboarding mistakes increases.
C. Regardless of the number of weeks in class, the number of keyboarding mistakes does not change.
D. In general, decreased keyboarding mistakes do not affect the number of weeks in class.
(Graph Below)
Which statement about the scatterplot is true?
A. As the number of weeks in class increases, the number of keyboarding mistakes decreases.
B. As the number of weeks in class increases, the number of keyboarding mistakes increases.
C. Regardless of the number of weeks in class, the number of keyboarding mistakes does not change.
D. In general, decreased keyboarding mistakes do not affect the number of weeks in class.
2 answers:
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Givens
y = 2
x = 1
z(the hypotenuse) = √(2^2 + 1^2) = √5
Cos(u) = x value / hypotenuse = 1/√5
Sin(u) = y value / hypotenuse = 2/√5
Solve for sin2u
Sin(2u) = 2*sin(u)*cos(u)
Sin(2u) = 2() = 4/5
Solve for cos(2u)
cos(2u) = - sqrt(1 - sin^2(2u))
Cos(2u) = - sqrt(1 - (4/5)^2 )
Cos(2u) = -sqrt(1 - 16/25)
cos(2u) = -sqrt(9/25)
cos(2u) = -3/5
Solve for Tan(2u)
tan(2u) = sin(2u) / cos(2u) = 4/5// - 3/5 = - 0.8/0.6 = - 1.3333 = - 4/3
Notes
One: Notice that you would normally rationalize the denominator, but you don't have to in this case. The formulas are such that they perform the rationalizations themselves.
Two: Notice the sign on the cos(2u). The sin is plus even though the angle (2u) is in the second quadrant. The cos is different. It is about 126 degrees which would make it a negative root (9/25)
Three: If you are uncomfortable with the tan, you could do fractions.
