a bathtub is 18 inches deep it takes 2 mins to fill up the tub 3 inches i think it will take 10 mins to fill up all the way am i correct?

No, sorry. Here's how to do the problem:

 

Let's list what we know: The bathtub is 18 inches deep.

It fills up 3 inches in two minutes.

 

So, if it fills up 3 inches in two minutes, we can write that as the tub filling up 3/2 (or 1.5) inches/minute.

 

Now, how LONG does it take to fill up?

18 inches     3 inches

------------- = -------------

x minutes     2 minutes

 

We're solving for x, so let's cross multiply.

(2 minutes)(18inches) = (x minutes)(3 inches)

The units cancel out because there's one on each side.

36 = 3x

Solving gives us x = 12.

 

SO it takes 12 minutes to fill up.