Question

If 39 is 1% of a number, what is that number?

Answer 1

3900

Explanation:

If you think of it logically, this problem is saying:
`x*1% = 39`
`1%` is `1/100` so it's
`x*1/100 = 39`
Divide both sides by `1/100` and you get
`x=39/(1/100)`
Remember that when there is a fraction in the denominator we flip it and multiply that on top and bottom:
`x = (39*100)/((1/100)*100)`
Therefore
`x = 3900`

You can check this by multiplying our answer by `1%`
`3900*.01 = 39`

Answer 2

3900

Explanation:

`color(blue)("Method 1: ratio")`

Note that `color(magenta)("100% is all of it")`. So we have:

`color(white)("d")`

`color(purple)("Initial ratio")`
`color(white)(".dd")color(purple)(darr)`
`obrace(" 39 : 1%") ->ubrace(100(39 : 1%))color(white)("d")= color(white)("d")3900:"color(magenta)(100%)`
`color(white)("dddddddddddddd")color(purple)(uarr)`
`color(purple)("Multiply everything inside the brackets by 100")`

`color(white)("d")`

So `"39 is 1% of 3900"`

`color(purple)("Alternative ratio format in fractional form:")`

`(1%)/39xx100/100 = (100%)/3900`

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

`color(blue)("Method 2: algebraic manipulation")`

Set the unknown value as `x`

Known that 1% is the same as `1/100`

Then `1/100xx x =39`

Multiply both sides by `color(red)(100/1)`

`color(green)(1/100xx x = 39 color(white)("ddd")-> color(white)("ddd")1/cancel(100)^1 color(red)(xx cancel(100)^1/1)xx x =39 xx color(red)(100/1)`

`color(white)("dddddddddddddd")->color(white)("dddddddddddddddddd")x = 3900`