The following week, Mary cycled off in another direction on Saturday morning. She left her home at 9 am and cycled 60 miles at a constant speed of 7 miles per hour until she reached a guesthouse. She spent Saturday night in the guesthouse and cycled back home on Sunday morning, starting from the guesthouse at 9 am and cycling back home along the same route as the day before at a constant speed of 13 miles per hour.
The solution of a well-known puzzle says that Mary will pass some point along the route at exactly the same time on both Saturday and Sunday. How many hours after 9 am will this happen?
TIP: When you've figured out the time, remember to check that Mary will be the same distance from home at that time on both days.
2007-02-05 08:48:31 · 3 answers · asked by mad dawg 1 in Science & Mathematics ➔ Mathematics
It will be the time that the sum of the distances exactly equals a trip.
7t + 13t = 60, t = 3
2007-02-05 08:54:23 · answer #1 · answered by sofarsogood 5 · 0⤊ 0⤋
(7 + 13)*t = 60, so t = 3 hours.
The meeting point is 21 miles from home, 39 from guesthouse. They meet after 3 hours.
I speek about meeting for the best way to think on this problem is to imagine that Mary and a clone of hers start from their respective points at the same time the same day. Date is irrelevant here.
2007-02-05 16:57:13 · answer #2 · answered by Jano 5 · 0⤊ 0⤋
1.9
2007-02-05 17:55:19 · answer #3 · answered by billy p 1 · 0⤊ 0⤋