transfer price

sir in my exam i got a question on transfer pricing , Question very similar to man co question in bpp . but sir in that question the production capacity of producing division was limited say 300000 but the external demand from producing division was 240000 and internal demand was 100000 , that say we need 340000 but we can only produce 300000 , so what to do now . there was a transfer price there already and question asked to use that . what i did is produce 240000 externally because it gave a higher contribution per unit ( there was no bottleneck here ) than internally and the rest internally 60000 because it gave lesser contribution per unit . was my approach correct ?