Triple trouble

Logic Level 1

Al, Ben and Chuck, the Davis triplets, are out for a walk. As always, they're wearing identical outfits. The only way to tell them apart is by talking to them: Al always tells the truth, Ben sometimes tells the truth, and Chuck always lies.

As they pass you walking single-file, you ask who's who today.

Triplet in front: "The triplet in the middle is Al."

Middle triplet: "I'm Ben."

Triplet in back: "The triplet in the middle is Chuck."

From front to back, what is their order?

Ben front, Chuck middle, Al in back Chuck front, Ben middle, Al back Al front, Ben middle, Chuck back Al front, Chuck middle, Ben back Chuck front, Al middle, Ben back Ben front, Al middle, Chuck back

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Denton Young by Denton Young , 47, USA

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6 solutions

Denton Young
Jun 8, 2015

Clearly only one triplet is telling the truth, since the middle triplet can only be one of them. The truth-teller must be Al.

Al cannot be in front, since he would be telling a lie. If he's in front he can't also be in the middle.

Al cannot be in the middle: he would be lying about being Ben.

Therefore Al is in back. Since his statement is true, the twin in the middle is Chuck. Therefore Ben must be in front.

7 Helpful 0 Interesting 0 Brilliant 0 Confused
Gem Rose
Jun 9, 2015

The first triplet states: 'The triplet in the middle is Al' But he says : 'I'm Ben'. Obviously they are both lying which means Al is in the back. He says: 'The triplet in the middle is Chuck' So, because he always tells the truth, that means Chuck is in the middle, Which leaves Ben to be in the front.

2 Helpful 0 Interesting 0 Brilliant 0 Confused
Liz Strautman
Aug 6, 2015

The middle one cannot be Al,because he claims to be Ben. (Al can't lie). The one in the front is lying by saying that the middle one is Al, which makes him also not Al. That means Al must be in the back. He's telling the truth, so Chuck is in the middle, leaving Ben as the leader.

1 Helpful 0 Interesting 0 Brilliant 0 Confused
Varun M
Jun 8, 2015

The question says Al always tells the truth ;Al can't be the first because then he would be telling a lie nor can he be in the middle because he would have to lie about his identity. So, the third is Al ,second is Chuck(Al;s comment) and first is Ben

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Sandeep Dara
Jun 18, 2015

Al always tells truth. If Al is in the front he cannot say that the middle on e is Al, so Al is not in the front. Al cannot be in the middle as well because he would be lying. Therefore Al is in the back. Since Al always tells the truth, the middle one is Chuck. So the front one is obviously Ben. Therefore the order is Ben, Chuck, Al.

0 Helpful 0 Interesting 0 Brilliant 0 Confused
Punyasloka Panda
Jun 14, 2015

If the front one is Al then he cannot tell himself to be in the middle. Moreover, Al is the one who speaks truth always. Al cannot be in the middle as he cannot lie to be Ben. So Al is at the back. Chuck is in middle as per Al's statement. Chuck always lies. So it is all ok if he says himself to be Ben. And Ben has to be in front and he seldom tells the truth. So this time he has not.

0 Helpful 0 Interesting 0 Brilliant 0 Confused

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