Question

. x is directly proportional to y. When x = 5, y = 3. Work out the value
of y when x =9

Answer 1

Answer: y = 5.4

Step-by-step explanation: This is a proportional statement. So we can set up a system of proportions.

So we know when x is 5, y is 3. Thus, we can set up a proportion
`(x)/(y)` such that substituting will give
`(5)/(3)`.

Now, we know when x is 9, y is some unknown number. So we can set up the second proportion as
`(9)/(y)`.

Since 5/3 and 9/y are directly proportional, these 2 expressions are therefore equal. So we have
`\frac{5}3}`
`= (9)/(y)`.

Cross multiplying, we get
`5y = 27`.

Dividing by 5, we get
`y = 5.4`

Hope this helped!