When bill bought a marigold plan it was 1/4 inches tall after the first week is was 1 1/12 after the second one it was 1 11/12 inches after week three it was 2 3/4 inches what was the night of the plant at week 4?

Let's come up with points that would be on the graph of a str. line:

(0, 1/4), (1, 1 1/12), (2, 1 11/12), (and so on).

Assume that this is a line, a str. line, and not a curve.  

The slope of this line is

        1 11/12 - 1 1/12
m = = 10/12, or 5/6.
               2 - 1

We now have the slope and y-intercept:  slope = m = 5/6; intercept = 1/4.

The line is then    y = (5/6)x + 1/4.

To answer this question, substitute 4 for x and calculate y:

   y = (5/6)(4) + 1/4 = 20/6 + 1/4   =  40/12 + 3/12   =   43/12 inches.

That's 3 7/12 inches.