Question

If y is inversely proportional to x and y = 4 when
x = 3,
(i) express y in terms of x,
(ii) find the value of y when x = 6,
(iii) calculate the value of x when y = 24.​

Answer 1

Answer:

When something is inversely proportional it can be solved by using the equation:

y = k/x

where k is the constant.

So using this we can plug in x and y to find the value of k.

3 = k/4.

Next we isolate k and find that k = 12. Now we use this to find the value of y when x = 8. Plug in x and you get y = 12/8 or y = 3/2 or 1.5.

Another way to solve this is to look at how the value of x changes. When the value of x goes up, the value of y goes down. In other words, when x is multiplied by some number, y is divided by that number. In this equation we can see that x is multiplied by 2 to go from 4 to 8. Thus, y must be divided by 2. Thus, y = 3/2 or 1.5.