There are three envelopes and exactly two statements are written on each of the envelopes. The statements on one of the envelopes are BOTH TRUE, the statements on the other envelope are BOTH FALSE and the remaining envelope has ONE TRUE and ONE FALSE statement. Here is what is written on the three envelopes:

First Envelope:
(a)The formula is not in here.
(b)The formula is in Envelope 2.

Second Envelope:
(a)The formula is not in Envelope 1.
(b)The formula is in Envelope 3.

Third Envelope:
(a)The formula is not in here.
(b)The formula is in Envelope 1.

Which envelope contains the formula ?

(In reply to Is it that straightforward? by Andrew F)

oops. misread. sorry
1 mixed 2 true 3 false

1 the formula is not in 1 (tue), nor in 2(so a flase assertion) (mixed if in 3)

2 The formula is not in 1(true), but in 3(true) (true if in 3)

3 the formula is in 3(so, not not in3-false) and not in 1 (also a false) (therefore 3 is both false)
Got it. Sorry about the last post.

Posted by Andrew F on 2003-04-11 17:30:45