Hello Caleb.
The difference of the speeds of tiger and prey is 50-25 = 25mph that means tiger would get 25 miles close to its prey in 1 hour. Since their distance is 0.25. you can set up a proportion;
25/1 = 0.25/x; x = 0.01h =60*0.01 = 0.6 min or 36 sec.
hope that helps