i think you should take a fruit from the mixed box. since all labels are false you know what should be in the box that says mixed (which is false). so if you pick an apple, that box is filled with apples. and because all of them must be false, the box where you took the label from that sais apples is not apples and also not the mix one(because then you can't swap pear anymore).
to make it short: you take from mix, if it's apple, the one that sais mix is apple, the one that sais apple is pear and the one that sais pear is mixed ;)
finally i can post a riddle myself
i'll do a freestyleversion of one i know
mr woo, skora, JF and TF walk in the middle of the night. it's completely dark and they have one flashlight. then they see a bridge which leads to freestyle-paradise whatever. a sign sais the bridge has holes, so you need to have the flashlight with you if you walk on it. also it sais that only 2 persons can walk on the bridge at the same time and somehow they know that it takes 12 minutes before the bridges collapses.
mr woo is old and for him it takes 5 min to cross the bridge
skora can only walk while doing htw, so it takes him 4 min to cross
JF is a normal healthy guy so it takes 2 minutes for him
TF is young and energetic so he can do it in only 1 minute.
off course you understand people have to come back to return the flashlight. how do the 4 get to the other side? ;)
