Answer:
1. If x varies directly as y, and x = 9 when y = 6, find x when y = 15.
x= k/y
9= k/6
k=(9)(6)
k=54
x=54/15
x = 3.6
2. If x varies inversely as y, and x = 5 when y = 4, find x when y = 2.
x=k/y
5=k/4
k=(5)(4)
k=20
x=20/2
x=10
3. If x varies jointly to y and z, and x = 30, y = 2 when z = 5, find x
when y = 4 and z = 8.
x=kyz
30=k(2)(5)
30=k10
k= 30/10
k=3
x=(3)(4)(8)
x=96
4. If x varies directly to y and inversely to z, and x = 10, when y =
15 and z = 3, find x when y = 20 and z = 5.
x=ky/z
10=k(15)
3
k15=(10)(3)
k15=30
k=30/15
k=2
x= (2)(20)
5
x= 40
5
x= 8
