4) 1 mi/6min * 60 min/1h = 1/10 mi/h = 0.1 mi/h
5) 175 mi *1 h/50 mi = 3.5 h
6) Mr. Smith - 9 min -from school to the park.
Mr. McNeil walks twice as fast, that means if s is a speed of Mr. Smith,
then 2s is a speed of Mr. McNeil.
Distance from school to the park = 9*s, distance from school to the park and back = 2*9*s.
Time= Distance/Speed
For Mr. McNeil:
Time from school to the park and back= distance from school to the park and back/ speed of Mr. McNeil = 2*9*s/2s = 9 min.