Explanations:
The formula for calculating the speed of both Barry and Robin is given as:
For Barry:
Distance covered = 2 miles
Time taken = 30 minutes = 0.5 hr
The unit rate in minutes per mile is given as:
Hence the unit rate in minutes per mile for Barry is 15min/mile
For Robin:
Distance covered = 3 miles
Time taken = 36 minutes
The unit rate in minutes per mile
Hence the unit rate in minutes per mile for Robin is 12min/mile
Since Robin covered 1 mile in 12minutes (less time than Barry), hence Robin walks faster