Variable Cost and Total Contribution

1. In question 1, I have assumed its only the Tashtego that makes the trip of Balik to Singapore and back. I have also assumed the relevant cost is the cargo cost only. Therefore, profit contribution of carrying I ton of tapioca from Balik and Singapore:

Expected revenue $5.10 Less freight cost (0.25+0.56) 0.81 Profit Contibution 4.29

From Singapore to Balik:

Expected Revenue $2.70
Less freight cost (0.16+0.32+0.14) 0.62
Profit Contribution 2.08

2. Total contribution of Tashtego for round trip is:
From Singapore to Balik=(2.08*3150)= $6552
From Balik to Singapore=(4.29*3950)= 16946
Total contribution 23498

If we assume same contribution profit as Tashtego, then big vessel total contribution is:
From Singapore to Balik=2.08*6850)= $14248
From Balik to Singapore=(4.29*6850)= 29387
Total Contribution 43635

3. Incremental trip costs of sending Tashtego on a round trip between Singapore and Balik is: Tashtego Trip cost
Note: Tashtego take 2.5 days in balik and 1 day in singapore

Balik Singapore Total
Portage (4500*0.14*2.5)=1575 (4500*0.2*1)=900 $2475
Lighthouse 73 126 199
Sea bunkering(0.73*1920 roundtrip)= 1402
Total per trip