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?

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.

To calculate the mean number of people who speak English only, we need to know the total number of people hired on the ship. Since we know that between 50 and 80 people are hired, we don't have a specific value for the total number, which means we cannot calculate the mean number of people that speak English only.

Without knowing the exact total number of people hired, we cannot determine the mean.