Who makes the most environmentally friendly choice?

Question

Three friends, Alicia, Ben and Chris, want to travel from Toulouse to London.

Alicia decides to ride her motorcycle from Toulouse city hall to Matabiau railway station, then she will go to Paris by train (TGV). She will arrive in Montparnasse railway station. From there she’ll go to Paris-Nord station on the Underground, and travel with the Eurostar to St Pancras station in London. Then she’ll use the tube to go to the British Museum.

Ben decides to drive from Toulouse city hall to Blagnac airport. Then he will fly to Heathrow airport, and take a cab to go to the British Museum.

Chris decides to drive from Toulouse city hall to Calais, and cross the channel on a ferryboat. Then he will drive from Dover to London. He will drive round to Regent’s park, park there and go down by foot to the British Museum.

To help you explain your answer you are given the following data:

Toulouse City Hall to Matabiau station: 1.5 𝑘𝑚.

Matabiau station to Montparnasse station: 713 𝑘𝑚.

Montparnasse station to Paris-Nord station: 5.3 𝑘𝑚.

Paris-Nord station to the Channel Tunnel: 333 𝑘𝑚.

Channel Tunnel: 88 𝑘𝑚.

Channel Tunnel to St Pancras station: 68 𝑚𝑖𝑙𝑒𝑠.

St Pancras station to the British Museum: 0.8 𝑚𝑖𝑙𝑒𝑠.

Toulouse city hall to Blagnac airport: 9 𝑘𝑚.

Blagnac airport to Heathrow airport: 886.17 𝑘𝑚

Heathrow airport to the British Museum: 17.1 𝑚𝑖𝑙𝑒𝑠.

Toulouse city hall to Calais: 965 𝑘𝑚.

Calais to Dover: 30.1 𝑚𝑖𝑙𝑒𝑠.

Dover to Regent’s park: 80.1 𝑚𝑖𝑙𝑒𝑠.

1 𝑘𝑚 = 0.621371 𝑚𝑖𝑙𝑒 and 1 𝑚𝑖𝑙𝑒 = 1.60934 𝑘𝑚.

CO2 emissions for the average Eurostar train: 11.2 𝑔 per passenger per km.

CO2 emissions for the average TGV train: 3.2 𝑔 per passenger per km. CO2 emissions for the average subway train: 3.8 𝑔 per passenger per km.

CO2 emissions for the average short-haul international flight: 26864 𝑔 per passenger per km.

CO2 emissions for a ferryboat for one average car: 750 𝑔 per mile.

grams of CO2 emissions for Alicia’s motorcycle per km (driver alone): 100

grams of CO2 emissions for Ben’s taxi per km (one passenger only): 222

grams of CO2 emissions for Chris’ and Ben’s car per km (driver alone): 169.388

Answer 1

This is a units conversion question. I'll do the one for Alicia and you can do the rest. What you want to do is keep your units straight. First I wrote out the itinerary connecting dots and labeling the cities/stations etc with mileage in between (in km or miles). Next you write out the values WITH the units.

For Alicia's motorcycle ride from Toulouse to Matabian Train Station I have: (1.5km)*(100g/km) . Notice how km will cancel out and you'll only be left with grams. We want to add all of the CO2 Emissions in grams for each leg of the journey, hence:

(1.5km)(100g/km) + (3.2g/km)(713km) + (11.2g/km)(333km) + (3.8g/km)(0.8miles)(1km/0.621371km) = 6166.09 grams of CO2 Emissions for Alicia. In every one of those sections of the trip, the units cancel out leaving only grams. Good luck with the rest of the problem.