Spring Scale Problem: Finding Time w/ Force & Mass

[DrDanger]

Homework Statement

You use a spring scale to pull a 1.5 kg object on a horizontal frictionless surface with a constant horizontal force of 1.3 N (according to the scale reading). You use a stopwatch to time how long it takes the object, starting from rest, to cover a distance of 2.7 m. What is the reading of the stopwatch?

Homework Equations

F=-KX
F=ma
$$\Delta X=volt+.5aT^2$$

The Attempt at a Solution

So I did a=F/m to get the acceleration then plugged that into $$\Delta$$ X=volt+.5aT^2 and Vo is equal to 0. After i plugged it all in I got 2.49, is that right? For some reason it seems wrong.

 

[DrDanger]

On a side note, is possible to find k using f=kx?