Uncertainty Principle of a nonrelatavistic particle

[Identify]

Homework Statement

If the uncertainty in the location of a nonrelativistic particle is about equal to twice its de-Broglie wavelength, show that the uncertainty in its velocity is greater than about 4% of its velocity.

Homework Equations

ΔpΔx>h/4Pi
p=mv
Δx=2nλ

The Attempt at a Solution

I've put the above equations together and manipulated them but I'm not really sure how to get to, Δv>0.04v using the above formulae. An indication of where to begin would be greatly appreciated.

 

[turin]

p=mv

You also have another equation for momentum from Quantum Mechanics.

Δx=2nλ

What is n?

 

[Identify]

n is an integer. n(lambda)=nh/p. So Lambda = h/p.
I have it now. Thankyou very much.