If y = 12 and x = 6, using an indirect variation, what is the value of y when x = 20?
When two variables change in inverse proportion it is called an indirect variation. In an indirect variation, one variable is constant times inverse of the other. If one variable increases other will decrease, if one decreases other will also increase. This means that the variables change in the same ratio but inversely.
The general equation for an inverse variation is y = k / x. Or k = xy which is constant. So the product of two variables is a constant for inverse variation.
y = 12 x = 6
y = k / x
12 = 72 / 6
Now we can calculate the value of y when x = 20
y = 72 / x
y = 72 / 20
y = 3.6
in a school, the ratio of the number of boys to the number of girls is 2:3 and the ratio of the number of girls to the number of teachers is 7:4. what is the ratio of the number of students to the number of teachers?
B : G = 2 : 3 G : T = 7 : 4
2 : 3 = x : 7
x = 4 2/3
B : G : T = 4 2/3 : 7 : 4
(B + G) : T = 11 2/3 : 4 | *3
(B + G) : T = 35 : 12
In ΔJKL, l = 1.3 inches, j = 4.8 inches and ∠K=77°. Find ∠L, to the nearest 10th of a degree.
Using the Law of cosines calculate the third side of a triangle JKL:
k2 = l2 + j2 - 2lj*cos(K)
And again, use the Law of cosines to find the measure of angle L:
l2 = j2 + k2 - 2jk * cos(L)