concentration question

[t35t]

For some reason, it seems the method to work out concentrations keep changing from one paper to another...
consider:
"A student wishes to determine the amount of potassium ion (K+) in a sample of soup using atomic absorption spectroscopy. She weights 2.65g of the soup and adds a small volume of water. The insoluble material is removed by filtration and washed with more water. The filtrate and washings are collected and the volume is made up to 250.0mL in a volumetric flask. She pipettes 25.00mL of this solution into a second volumetric flask and again makes the volume up to 250.0mL. When this second solution is sprayed into the flame of an atomic absorption spectrometer, a reading of 0.049 was obtained. 0.049 corresponds to 23.5mg/L

b)Determine the concentration of K+ (aq) in g/L, in the diluted soup solution,"ie the second solution" (sic)

I had used 23.5mg/L in the following way.
C(K+)=23.5mg/L x0.250
C(K+)=5.875 mg/250mL

Their answer simply does:
C(K+)=(23.5mg/L)/1000
C(K+)=0.0235g/L

for
c)What is the concentration of K+ (aq) in g/L, in the first volumetric flask?
I did:
C(K+) in25ml aliquot= (5.875 mg/0.250L)x (250/25)
C(K+) in undiluted: 58.75mg/25mL

In part D, where I was required to find the % of K in the sample, I had gotten the answer write despite getting the previous parts 'wrong'

The reason why i hadn't actually divided my figures by the 25 or so... was because of in a few other practice exams, when I look at their methods, they leave the answer as it is- observe:
A mass of 0.1375g of a freeze-dried sample of shellfish is dissolved in 2.0mL of nitric acid, heated for 3 hours at 112.5degrees and transferred to a 500mL volumetric flask, where it is made up to the calibration line with deionised water. A volume of 1.00mL of this solution is further diluted to a 250.0mL in a second volumetric flask. AAS is used to measure the absorbance of this solution, which is found to be 1.03 corresponding to 0.35ug/L

-both questions involve 250mL volumetric flasks in which both are subjected directly to AAS- however, the accepted answer for the second question is

C=0.35x10^-6g/1000mL
C=0.0875x10^6g/250m/L
- I noted that in the other exam, the determined mass was then divided by 250, where as in the second question, the mass found directly correlates to the amount in the 250mL flask.

Having read my long, long post, which one is more correct? Would my answer have been correct anyways? (for the first question that is)

I hope I haven't been too convoluted/ambiguous.