How do you write an equation of a line if it take Andrew 20 minutes to get from a depth of 400 feet to a depth of 50 feet?
We first have to translate to
We can take time as the
If we say Andrew started at time zero at a depth of 400 feet, this translates in a point
A straight line equation is of the form
First we determine
The change is from
(Remember: change is always calculated as new minus old)
Then divide the two:
In the original equation
Time 0, depth 400
So the total equation becomes:
Just to make sure you can also check if this is valid for the other point we know and see what happens if we fill in for
After how many minutes does Andrew reach the surface?
(tip: solve for