Question

Between 50 and 80 people are hired on a ship. 75% speak English only and 25% speak German only. What is the mean number of people that speak English only? Can this even be calculated?

Answer 1

min/max number of people hired
=50,80
Best estimate of number of people hired
=(50+80)/2=65
Best estimate of people who speak English only = 0.75*65=48.75, or approx. 49 persons

Note that sometimes the "best estimate" is interpreted as mean, which often is the best estimate.