My friend sets out walking at a speed of 3 miles per hour. I set out behind her 5 minutes later at 5 miles per hour. For how many minutes will my friend have been walking when I catch up to her?
Let the time it takes you to catch up to your friend==T
5T ==3 [T + 5], solve for T
5T ==3T + 15
5T - 3T ==15
2T == 15
T ==15 / 2 ==7.5 minutes -for you to catch up to her
7.5 + 5 ==12.50 minutes - your friend had been walking when you caught up to her.
+36915 5 min = 1/12 hr in five minutes your friend will have a 3 m/hr * 1/12 hr = 1/4 mile head start
You are walking two miles per hour faster and will take 1/4 m / 2 m/hr = 1/8 hr to catch her = 7.5 mins
7.5 + 5 = 12.5 mins
