Comments on: The Truck and the Plane

By: Dr. Hex

Dr. Hex — Sat, 11 Jan 2020 18:53:56 +0000

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.

By: Arjun

Arjun — Fri, 10 Aug 2018 10:34:24 +0000

The Plane arrived 10 minutes early .

It took 30 minutes for the truck to meet the bicycle and therefore will take 30 minutes back to the post office ( assuming the perfect system)

So the truck say left at 9 am and was back at the post office at 10 am when it should have been back at 10:20 am

The truck was scheduled to reach the airport at 9:40 am and be back at 10:20 — 40 minutes to go and 40 minutes to come in a perfect system

Plane was schedule to land at 9:40 am

By: Doug

Doug — Mon, 29 May 2017 00:30:03 +0000

40 minutes is the correct answer but it is not explained correctly in the published answer.
The published answer spuriously claims the truck had already driven 30 minutes to reach the bicycle which may or may not be correct but in any case is irrelevant.
The bicycle had been ridden for 30 minutes to meet the truck at a point when the truck was 10 minutes from the plane. Assuming instantaneous transactions, the plane landed 30 minutes before the bicycle met the truck, saving the truck 10 minutes of travel to the plane. There’s your 40 minutes. Why make it more difficult than that?

By: Bob

Bob — Mon, 01 May 2017 16:51:58 +0000

The grammar of the problem statement says truck had travelled 30 mins before meeting the bike,
at which point you cannot solve the problem since you need to know how long the bike travelled.
If you know how long the bike travelled, add it to the 10 mins to get your solution. For example,
let’s say the plane landed at 9:00am, bike travelled 30 mins and met truck at 9:30am, and truck
was expecting to meet the plane at 9:40am. So in that case, the plane arrived 40 mins early.
The wording of the problem needs to be fixed to not imply the truck was sent out 30 mins before
meeting with the bike.

By: Abhishek Patkar

Abhishek Patkar — Sat, 29 Apr 2017 08:53:53 +0000

Well,
Nowhere in the problem is it stated that the truck and the bicycle left from their respective locations at the same time. So I don’t understand why are we assuming that the truck had travelled for 30 mins.
The bicycle left as soon as the plane landed (instantaneous transactions). By the time bicycle reached the truck it is clear that it had been 30 mins. since the plane had arrived at the airport as the bicycle took 30 mins. to reach the truck. Had the bicycle been not there then it would have taken the truck further 10 mins
to reach the airport which adds to the 30 mins for which the plane had been at the airport. So assuming that the truck was scheduled to leave the post office so that it could reach the airport exactly at the time of the plane’s arrival, the plane had arrived 40 mins. before schedule.

By: Raj

Raj — Sun, 09 Apr 2017 14:47:10 +0000

Nowhere does the problem say that Bicycle traveled for 30 minutes …It’s the truck that travelled 30 minutes …so your statement …”Both the truck and the bicycle traveled 30 minutes toward one another” . …Is also an assumption …Neither is cycle speed mentioned ….So it could be a fraction of a second more than 10 minutes till endless time ….Depending on your imagination

By: Me

Me — Sun, 18 Dec 2016 16:47:23 +0000

I understand the answer.

BUT! You need to say transactions are instantaneous.

By: Jon

Jon — Sat, 23 Jan 2016 22:11:02 +0000

@Dan, the confusion from your answer is you keep suggesting that the problem is stating that the truck drove for 30 min before meeting the bike. That may be true but has no impact on the answer. The critical info is that the bike drove for 30 min before reaching the truck, which is stated in the question but not very clearly as to which drove 30 min.

If you don’t consider that the bike drove for 30 min, then the plane could have arrived a month early and it took the poor biker that distance to drive what would have taken the truck it’s remaining 10 minutes.

So the solution is: the truck saved 20 min so it met the bike 10 min short of the usual arrival time. Then add 30 min that the BIKE already drove and you get 40. It’s coincidence that the truck also already drove 30 min.

By: Dan

Dan — Mon, 28 Sep 2015 20:04:26 +0000

Leon, you need to forget about speed. It’s confusing you (and others) and completely orthogonal to the problem. All you information you need to solve it is provided in the problem. Maybe it’s not clear to you that the post office truck left at the usual time to meet the plane when it landed?

Both the truck and the bicycle traveled 30 minutes toward one another. The truck returned 20 minutes early. This means if the plane hadn’t arrived early, the truck would have had to travel another 10 minutes to get to the airport and 10 minutes to return to the spot where they met (10 minutes + 10 minutes = 20 minutes early). That’s the 20 minutes the truck saved.

I highly recommend you (or anyone else who is working on this) sketch a diagram of the problem. It will make it easier to understand the solution.

It doesn’t matter if Superman is riding the bicycle. All you know is the truck met the bicycle 10 minutes from the airport. How do we know this? Because the truck would have driven the remaining 10 minutes to the airport, picked up the items, then driven 10 minutes back to the spot where they met, and returned to the Post Office at his normal time.

In other words, the bicycle met the truck at a point that saved the truck 20 minutes of driving time. The speeds are irrelevant (other than being constant).

I hope that makes it clearer.

By: Leon

Leon — Mon, 28 Sep 2015 17:41:57 +0000

Still doesn’t make sense. You can’t calculate the answer using only the original information, you need to know how fast the bike and the truck are travelling relative to each other.

Let’s say Superman is riding the bicycle and it’s travelling 10x faster than the truck. The plane could have landed 1 minute ahead of schedule and the truck would still be back 20 minutes early. In that 1 minute, the bike would have carried the parcel the same distance as the truck would have in 10 minutes, saving it a journey time of 20 minutes in total.

Your solution only makes sense once you tell us that the bike is travelling 1/3 of the speed of the lorry. Without that information, it’s impossible to determine how early the plane lands.