Not too hard: a maths problem

B1 and B2 went to visit each other. They left their houses at the same time. When they met on the way, they forgot they wanted to see each other and kept on walking. B1 reached B2's house 8 minutes after the meeting and B2 got to B1's house 18 minutes after the meeting. How long did it take B2 to reach B1's house from the time he left his own house?

...

Who else can work it out...

Kedaman? gooddreams?

me being the simpleton that i am, i'm gonna say 26mins :)

There does not seem to be enough data to solve this problem. I think for a given total time for the B1 trip, there is a fixed total time for the B2 trip.

When I assumed a B1 total time of 20 minutes, I got a B2 total time of 30 minutes not matter what B1 velocity I assumed. This agrees with the Kedaman answer.

When I assumed a B1 total time of 26 minutes, I got 26 miniutes for the total B2 time. this agrees with the Nullus answer.

When I assumed a B1 total time of 32 minutes, I got a B2 total time of 24 minutes.

30 mins by my calculations so keda is right. not a bad little puzzle though silv.

Kedaman is right. I discovered an inconsistency in my calculations.

There seems to be enough data to solve this problem.

I liked this one.

how did u guys solve it?

Quote:

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Originally posted by nullus
me being the simpleton that i am, i'm gonna say 26mins :)

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That was my first thought too...but then i figured why would anyone post such a stupid question if the answer is that simple...how did u people figure that out?

Code:

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B1:
 time:    x      8
      |--------|---------|     
 pos:    S1      S2
B2:
 time:    x      18
      |--------|-------------------|
 pos:    S2      S1

Speed:
B1=S2/8=S1/x
B2=S2/x=S1/18

S2/S1=8/x
S2/S1=x/18

x^2=8*18
x=12
total=12+18=30

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Kedaman's approach is the way to do it. However you can also do it this way too. I just assumed 10 km betweem B1 and B2.

VB Code:

Private Sub Command1_Click()
'Assumed 10 km between B1 and B2
Dim KmPerHourB1&, KmPerHourB2&, MinToMeet@
Dim KMLeftB1@, MinAfterMeetB1@, KMLeftB2@, MinAfterMeetB2@
Dim KMAfterMeetingB2@, TimeBeforeMeetingB2@
 
 
For KmPerHourB1 = 70 To 20 Step -1
    For KmPerHourB2 = 70 To 20 Step -1
        MinToMeet = 10 * 60 / (KmPerHourB1 + KmPerHourB2)
        KMLeftB1 = 10 - MinToMeet / 60 * KmPerHourB1
        MinAfterMeetB1 = KMLeftB1 / (KmPerHourB1 / 60)
        KMLeftB2 = 10 - MinToMeet / 60 * KmPerHourB2
        MinAfterMeetB2 = KMLeftB2 / (KmPerHourB2 / 60)
        
        If MinAfterMeetB1 = 8 And MinAfterMeetB2 = 18 Then
        
            Debug.Print "B1 kph: " & KmPerHourB1; "    B2 kph: " & KmPerHourB2
            KMAfterMeetingB2 = 18@ / 60 * KmPerHourB2
            Debug.Print "B2 Travelled this many km after meeting B1: " & KMAfterMeetingB2
            TimeBeforeMeetingB2 = (10 - KMAfterMeetingB2) / (KmPerHourB2 / 60)
            Debug.Print "B2 travelled for this many minutes before meeting B1: " & TimeBeforeMeetingB2
            Debug.Print "Total Time B2: " & 18@ + TimeBeforeMeetingB2
            
        End If
    Next KmPerHourB2
Next KmPerHourB1
 
End Sub