What Went Wrong in My Elastic Collision Calculation?

[VitaX]

Homework Statement

Homework Equations

V1f = (m1 - m2 / m1 + m2) * V1i
V2f = (2m1 / m1 + m2) * V1i
.5mVi^2 + mgyo = .5mVi^2 + mgy1

The Attempt at a Solution

V1 = (2gyo)^(1/2) = (2*9.8*.34)^(1/2) = 2.5815 m/s
a) V1f = (.650 - 4.40 / .650 + 4.40) * 2.5815 = -1.917 m/s
b) V2f = (2*.650 / .650 + 4.40) * 2.5815 = .6645 m/s

I don't understand why part a is wrong and part b is right. Doesn't make any sense to me since the question is asking for the speed after the collision in both part a and b. What did I do wrong?

 

[Delphi51]

I worked out v1 independently and got -1.918.
Surely the 4th digit difference is not significant?
I used 9.81 for g and got 2.583 for the initial speed.

 

[VitaX]

I worked out v1 independently and got -1.918.
Surely the 4th digit difference is not significant?
I used 9.81 for g and got 2.583 for the initial speed.

My teacher told us to input a lot of digits to be sure our answer is recognized since there is a 2% tolerance built in. Either way our answers would match. I think there must be something wrong with the system to say it is wrong.