Question

If a kilometer is equal to .621 miles, how many kilometers is one mile equal to?

Answer 1

See a solution process below"

Explanation:

We can write this relationship as:

`1"km" = 0.621"mi"`

We can now divide each side of the equation by `color(red)(0.621)` to solve for `1"mi"` while keeping the equation balanced:

`(1"km")/color(red)(0.621) = (0.621"mi")/color(red)(0.621)`

`1.610"km" = (color(red)(cancel(color(black)(0.621)))"mi")/cancel(color(red)(0.621))`

`1.610"km" = 1"mi"`

one mile is about 1.610 kilometers

Answer 2

The count of kilometres in 1 mile is `1.610` to 3 decimal places

Explanation:

Let the unknown count of kilometres be `x`

Use ratio in fraction format.
We need kilometres so put them at the top (numerator position)

`("kilometres")/("miles") -> 1/0.621 =x/1`

`color(brown)("This is where the shortcut comes from:")` `color(brown)("If we change the 0.621 int0 1 and do the same to"` `color(brown)("the top we will have our answer")`

`x/1 = (color(green)(1-:0.621))/(0.621-:0.621) = (1.610305.....)/1`

The question uses 3 decimal places so we need to do the same:

`1.610` to 3 decimal places

`color(brown)("Shortcut")`
Just divide the bottom into the top `color(green)(1-:0.621)`