## The Truck and the Plane

A delivery truck from the post office is sent to the airport to meet a cargo plane at its planned arrival time. The plane lands ahead of schedule and its contents are brought toward the post office by bicycle. After a half hour, the bicycle meets the truck and the mail is transferred.

The truck returns from the post office 20 minutes early. How early did the plane arrive? (Assume all transactions are instantaneous)

The delivery truck arrived back 20 minutes early, so it would have taken 20 minutes to go from where it met the bicycle to get to the airport and back. Therefore, the bicycle and truck met when the truck was 10 minutes from the airport. Adding those 10 minutes to the 30 minutes the truck had already driven to meet the bicycle means the plane arrived 40 minutes ahead of schedule.

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16 Comments on "The Truck and the Plane"

Dr. Hex says
January 11, 2020 @ 13:53

Some of yall are in real need of help. Sorry but you are. It is stated that all transactions are instant, therefore you also must assume that any and all other variables (ie speed of travel) are constant as well, so it doesnt matter if billy joe jim bob were walking or if he was riding a moped only the time traveled is relevant. Simple break down of timeline logistics:
Plane arrival 9:40am
we know that it takes 40 minutes for the truck to get to the airport, so this means he has to leave at 9:00am. still with me?
The truck we know drove for 30 minutes where he met billybob and got the mail. this means they met at 9:30..Now this also means that it is a 30 minute trip back home, so this puts him back at office at 10:00am…
On a normal basis the timeline would show as follows :
truck leaves 9:00am meets plane at 9:40am returns to office 10:20am Still following or do i need to get some sesamestreet characters to help?
On this day time line is this:
leaves 9:00am meets billy at 9:30am returns to office 10:am…
Now hopefully all can do the simple math here that the difference in when the truck was back at office was 20min….this is as simple as an explanation gets. If you can still argue i am wrong then please, i want to see your formula and where you went to school, so i know where not to send my kids.

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