Jennifer rode her bike at 12 miles per hour for 4 hours, then put her bike down and began walking at 3 miles per hour. Thomas started walking at 4 miles per hour along the same path at the same time that Jennifer started biking. When he reached the bike, he began riding it at 10 miles per hour. How many hours will it have been since they started when Thomas catches up to Jennifer?
INn FOUR hours Jennifer will travel 12 m/h x4 = 48 miles
it will take Thomas 48 miles / 4 m/hr = 12 hours to reach the bike
in the meantime Jennifer has EIGHT hours of walking 3 m/hr x 8 = 24 miles form the bike
Thomas now sets out at 10 m/h this is 10 - 3 = 7 m/h faster than Jennifer is walking
he will close the 24 miles and catch Jennifer in 7 m/hr *x = 24 m
x = 24/7hours
So Thomas walks for 12 hours then bikes for 24/7 hr = 15 3/7 hrs = ~ 15 hr 26 min