Analytical Question Help!!!!!

Seifer28 SG

A lot of money was stolen from a bank and driven away in a van. Three suspects A, B and C were brought to the police station for questioning and the following facts were established:

(a) No one other than A, B, C was involved in the robbery.
(b) A is innocent only if B is innocent.
(c) A does not know how to drive.

Can the guilt of any of the three be established? If so, which?

gd4u SG

Hmm, i very free... let me dig up my notes ..

A not certain
only B can be said to be guilty
statement (B) implies: C innocent -> B innocent/ guilty
C guilty -> B guilty ...

Laughing

alexkusu SG

As above Cool

Seifer28 SG

thanks!!!!!!

bladez87 SG

wtf dont understand?

is it C and not A?

Icemoon SG

don't understand your line of logic. especially your statement B.

ha8n SG

our first line already state NO ONe other than A,B, C are involved in robbery >>

n the question ask ?? guilty >> thus its

A < B < C

bladez87 SG

same

i was thinking, if C is innocent, B might be guilty or innocent, but if C is guilty, why B is guilty?

Icemoon SG

My take .. hope this is not a qian bian question.

Premises:

1. A is innocent.
2. B innocent -> A innocent => A guilty -> B guilty

So let's draw a truth table. Let 1 be innocent and 0 be guilty.

A B C
1 1 1
1 1 0
1 0 1
1 0 0
0 1 1
0 1 0
0 0 1
0 0 0

The rows in red will be true because there is no contradiction. According to premise 2, B -> A. The only time it is false is when B is 1 and A is 0. But this wrong scenario is not possible because we have established that A is innocent. C can be 1 or 0, as long as the row does not contain all 1 (because not all can be innocent).

Conclusion: no one's guilt can be established.

Make sense?

Icemoon SG

His reasoning is fallacious because he is denying the antecedent.

mystiv SG

seems like a lack of info...

and well, ice's explanation is simple yet detailed..nice one Wink

dinky1409 SG

Statement (a) could established that all 3 of them are guilty right?

Icemoon SG

huh .. why leh?

Statement (a) only tells us the murderer(s) must necessarily come from the group.

gd4u SG

Cos every piece of worksheet ...

they will jumble up the statement squence to make it look new ...

sry, i missed out on tt ...

hisoka SG

no conclusion can be drawn.

1) the facts may not be true cos they were just ascertained by pple

2) more than 1 person may be involved

3) a person who does not know how to drive can still drive.

4) the robbery may have been conducted by aliens

etc

fymk SG

A B C involved or suspected? If they are all involved - their guilt is already established.

If the robbers definitely come from A B or C , then :
Statement 1 : A =B = innocent (red herring? ) OR A=B = guilty
Statement 2 : A does not know how to drive and yet involved in the crime , B is definitely guilty as well.
Statement 3: C could be possibly innocent or guilty independently of A and B.

BUT it already stated that they ALL are involved in (a). So that discounts C's innocence. Guilt by association Smile

The only thing you can establish is the getaway driver : B or C could be the possible getaway driver.

fymk SG

Murderer? Nah look at your notes. Different context. Smile

Icemoon SG

sorry .. should be robbers hor. Embarassed

but no issue really .. 'cos this is a logic question. Laughing