Ruth Alexander examines US Secretary of State, John Kerry’s claim that 40% of the world’s workforce will be in Africa by 2050 and talks to the chief of the United Nations’ population division about its projections for 2050 and 2100. The programme also examines the final scene in The Fast and the Furious 6, the global box office sensation. How long must that runway have been at the end of the film? This programme was first broadcast on the BBC World Service.