Question

Worth 20 points try to answer as many as possible

tell me which one you are answering and tell me how you got the answer and your work

1) y varies INVERSELY with x. If y= 40 when x= 16, find x when y= -5.
2) y varies DIRECTLY with x. If y= 15 when x= -18, find y when x=1.6.
3) If x and y vary DIRECTLY, as x DECREASES, what happens to the value of x?
4) If x and y vary DIRECTLY, as y INCREASES, what happens to the value of x?

Answer 1

1) x = (40/-5)*16 = -128
.. Since the variation is inverse, (old y)/(new y) = (new x)/(old x). Note the new/old ratios are upside down. Thus (new x) = (old x)*(old y)/(new y), as above.

2) y = (1.6/18)*-15 = -1 1/3
.. Since the variation is direct, (new y)/(old y) = (new x)/(old x)

3) x DECREASES
.. When variation is direct, both variables move in the same direction. Here, the problem statement tells you what happens to x! (Perhaps a typo?)

4) x INCREASES
.. See 3).