快猫短视频

#167 This escalated quickly

At the shopping mall, while their mother鈥檚 attention is conveniently fixed on a window display, Jill furtively approaches her brother.

鈥淗ey, what do you say to a race up to the next floor and back? Winner does the other one鈥檚 chores.鈥�

鈥淵ou鈥檙e on,鈥� says Jack.

There are two escalators that move at the same speed, one going up and one going down, and also a regular set of stairs.

The children decide that each will choose on which of the three they want to race, but whatever they pick, they will have to run both up and down on that choice. Jack knows he can run upwards and downwards at about the same speed (and much faster than the escalator).

Which of the three methods should he choose for the race: the up escalator, the down escalator or the stairs?

Solution next week

#166 The week link

Solution

The days of the week in order are Ardik, Deldik, Curdik, Bordik, Endik, Gandik and Fordik (ADCBEGF). The three orders presented were (1) ABCDEFG, (2) DBACEGF and (3) GDCBAFE, and we know that in each case three are correct.

As nine are correct in total, but there are only seven days in the week, at least two days must be correct in two lists, and since the first guess was in alphabetical order and we know A is the first day, only two more days can be in the correct alphabetical position. This also means that each day must have been named in the correct position by at least one child. The third day can鈥檛 be A, so it has to be C. This leads to the fourth day being B, the second D and the rest follows.