finding final velocity in a perfectly elastic collision

ilovedeathcab

~~~Two marbles with equal masses collide. Marble A has an initial velocity of 1.69 m/s while marble B is initially at rest. If marble A comes to rest as a result of the initial collision, what is the final velocity of marble B?

* DO NOT include units in your answer.
* Give your answer with two decimals.
* Answers will be accepted if they are within 0.02 of the correct answer.

~Can anyone clarify this?
1. m1v1i + m2v2i = m1v1f + m2v2f

masses cancel....
2. v1i+v2i = v1f+v2f

3. (1.69m/s) + (0m/s) = (0m/s) + v2f

4. 1.69 m/s= v2f

I'm not sure this is correct...

LowlyPion

Looks correct.

ilovedeathcab

thank you so much!!!