Physics Elastic Potential Question

[leflyi]

This is from the VCAA 2007 exam.
However, in this example I found it through the 2013 Checkpoints.

In a laboratory class at school, Lee is given a spring with a stiffness of 20 N m^–1 and unstretched length of 0.40 m. He hangs it vertically, and attaches a mass to it, so that the new length of the spring is 0.60 m.

Question 10
By how much has the potential energy stored in the spring changed?

Anyway, the main issue i have found is the existence of two separate answers. 
Checkpoints exclaim :

The change of energy is = 1/2(20)(0.7)^2 [extension + 0.1] - 1/2(20)(0.6)^2

= 1.3 Joules.

VCAA exclaim

Tha change of energy is = 1/2(20)(0.3)^2 [extension + 0.1] - 1/2(20)(0.2)^2

= 0.5 Joules.

I am currently unsure of the correct answer, and need verification. Thanks!

[Homer]

VCAA is right! as always 

[leflyi]

I felt as such, my calculations were heading in that direction..

Seems strange that such an error has occured in the publishing..OH well people are people, they make mistakes time to time..


Edit : tsk tsk tsk, pg 212 question solution 193 -> Vertical Velocity of the horizontal is due to 40 x cos(25) not sin.. I think