<span>At least one bear was sighted on 28 separate days in 40 day period total = 28/40 We're looking for the daily frequency of bear sightings, that's in the whole 40 day period.
Let's say 40 days period = 100%. Then what's 28 days? </span>
So the solution we're looking for would be (<span><span>28 days∗100) / </span>40 days = 70%</span>