this was a question on my test that i got wrong...can someone please explain it to me?

Question

A stock solution containing Mn2+ ions was prepared by dissolving 1.176 g pure manganese metal in nitric acid and diluting to a final volume of 1.000 L. The following solutions were then prepared by dilution.

For solution A, 50.00 mL of stock solution was diluted to 1000.0 mL.
For solution B, 10.00 mL of solution A was diluted to 250.0 mL.
For solution C, 10.00 mL of solution B was diluted to 500.0 mL.

Calculate the concentration of the stock solution and solutions A, B, and C

Answer 1

1.176g/l is 1176mg/l. That's the stock.
It's also 1.176 mg/ml

A. Therefore, 50 ml of stock contains 58.8mg. Solution A is 58.8 mg/l.
That's also 58.8 ug/ml

B. Therefore, 10.00 ml Solution A contains 588 ug (.588mg). Put that in a quarter of a litre and you get 2.352 mg/l - Solution B.
That's also 2.352 ug/ml.

C. Therefore 10 ml solution B contains 23.52 ug. Put that in half a litre and you get 47.04 ug/l.

I think that's right, but I've had two kids interrupt me at least 5 times during the course of typing this, so you might want to check my math.