Maths puzzle two.

[EddieM]

I think I might of done this before.

You have 4 people on one side of a gorge.

They must cross a bridge to get to the other side.

The bridge is rickety and unlit, so must be crossed with someone carrying a torch.

The bridge can only take 2 people max at a time

The bridge will collapse in 17 mins and 10 seconds.

The 4 people are of different abilities.

a) can cross in 1 min
b) can cross in 2 mins
c) can cross in 5 mins
d) can cross in 10 mins

all crossing timings are one way.

How do you get everyone across in the allotted time?

 

[HawkEye244]

If you send 10 and 1 at the same time that takes 10 minutes. But send 10 before 1.

Send 5 and 2 at the same time that takes 5 minutes. But send 5 before 2.

1 can hold the torch for 10 for something to do.

2 can hold the torch for 5 for something to do.

Total crossing time 15 minutes.

 

[Notch7]

how many torches are there?

 

[EddieM]

If you send 10 and 1 at the same time that takes 10 minutes. But send 10 before 1.

Send 5 and 2 at the same time that takes 5 minutes. But send 5 before 2.

1 can hold the torch for 10 for something to do.

2 can hold the torch for 5 for something to do.

Total crossing time 15 minutes.

Nope, you have to have a torch at all times to cross.

 

[EddieM]

how many torches are there?

1

 

[SammyInnit]

1 and 2 cross together, 1 returns with the torch (3mins)

5 and 10 cross together, 2 returns with the torch (12mins, 15 total)

1 and 2 cross, 17 minutes.

 

[EddieM]

1 and 2 cross together, 1 returns with the torch (3mins)

5 and 10 cross together, 2 returns with the torch (12mins, 15 total)

1 and 2 cross, 17 minutes.

Jolly good, it's a Bloomberg interview question.

 

[SammyInnit]

Jolly good, it's a Bloomberg interview question.

It did take me a while but many a problem solved on the John.

 

[EddieM]

It did take me a while but many a problem solved on the John.

Not so clever if you have a couple of mins to come up with the answer. I know loads of folk who worked for Bloomberg, they all hated it.

 

[EddieM]

and so it goes on.

There is a pile of twelve coins, all of equal size. Eleven are of
equal weight. One is of a different weight. In three weighings find
the unequal coin and determine if it is heavier or lighter.

(This one is fairly easy)

 

[Bodd]

A gives D a piggy back
A then goes back with touch and gives C a piggy back.
A then goes back for B and cross with plenty of time drinking an English sparkling Wine, laughing and Five-ing

 

[EddieM]

A gives D a piggy back
A then goes back with touch and gives C a piggy back.
A then goes back for B and cross with plenty of time drinking an English sparkling Wine, laughing and Five-ing

A&D > 10 mins
< A 1 min
A&C > 5 mins
< A 1 min
A&B > 2 mins

19 mins

 

[bernardgreen]

A&D > 10 mins

Maybe A carrying D can cross in less than 10 mins,

If A can cross in say 2 minutes while carrying someone else then all crossings are completed in about 10 minutes.

 

[EddieM]

Maybe A carrying D can cross in less than 10 mins,

If A can cross in say 2 minutes while carrying someone else then all crossings are completed in about 10 minutes.

Nah X carrying Y slows them down to the slowest member.

 

[Bodd]

Nah X carrying Y slows them down to the slowest member.

If A was a big string man. D is a small baby. C is a 4 year old. . B was his wife.

All have different abilities