Crossing a bridge: solution

You are right: 17 minutes. 75 percent of our readers got the right answer.  The strategy works as follows: Mary and Joseph cross the bridge (2 minutes)Mary goes back (1 minute)Andrea and Benedict cross the bridge (10 minutes)Joseph goes back (2 minutes)Mary and...

How many triangles: solution

Exactly! There are 64.   You belong to the 75 % of our users who had the right answer.  Your feedback How did you like the puzzle? 1: not at all, …, 5: very much How difficult was it? 1: very easy, …, 5: very hard Send your...

Number sequence: solution

Make a list of all square combinations, e.g: 1+3=4, 1+8=9, 1+15=16, … Result: only 8 and 16 have just one square-partner! Start with any of those and the rest follows easily: 16 9 7 2 14 11 5 4 12 13 3 6 10 15 1 8.

MP3 player: solution

Let M be Milena’s amount of money, J denotes Jacob’s money and P the price of the MP3 player. We know that : P-37=J, J>0, P-2=M and M+J<P. So 2P-39<P, hence P<39. Since P is a whole number and J>0, then P=38.