Note that
108° = 90° + 18°
so
sin(108°) = sin(90° + 18°) = sin(90°) cos(18°) + cos(90°) sin(18°) = cos(18°)
Then
sin²(108°) + sin²(18°) = cos²(18°) + sin²(18°) = 1
by the Pythagorean identity.
Let b = blue marbles
y = yellow marbles
Sum = b+y
The <span>chance of a blue marble being drawn first is:
b / (b+y) = 0.55
</span>The <span>chance of a blue marble being drawn first then a yellow next is:
</span>b / (b+y) * <span>y / (b+y-1) = 0.37</span>
This can be solve easily by using a theorem of Bayes
0.37/0.55 = .67 or 67%
The appropriate choice is ...
... On Line 3, Brianna should have divided by 0.1 instead of subtracting 0.1.
_____
Had Brianna simplified her effort properly on line 4, she would have
... -0.1 +0.1x = -1.4
putting her essentially back where she started—with a 2-step equation.
Please explain.
As in taxi fares?
I think it's the first one. Two units right and three units down.