Which conclusions correctly use inverse proportion? Select all that apply.
Three identical independent workers pack one order in 20 hours, so five take 12 hours.✓Bonne réponse
Four identical independent mowers finish one field in 14 hours, so eight take 28 hours.
A fixed route takes 3 hours at 60 kilometres per hour, so it takes 4 hours at 80 kilometres per hour.
A fixed route takes 2 hours at 60 kilometres per hour, so it takes 1.5 hours at 80 kilometres per hour.✓Bonne réponse
Explication
The packaging job contains 3 times 20, or 60 worker-hours, so five workers need 12 hours; the fixed route is 120 kilometres, so travelling at 80 kilometres per hour takes 1.5 hours. The mowing claim is especially misleading because doubling an identical independent team should halve 14 hours to 7, not double it.