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He should hire 70 more men to complete the work in agreed time.
It helps if you have skills with balls. (j/k)
A man has been waiting for his girlfriend in the park Saturday morning for awhile but the girl didn't arive. He took a look at his watch when started to wait. He left when he saw the minute hand switched places with the hour hand on his watch. How long did he wait (h:mm:ss), knowing that he waited more than 1 hours ?
the snowman.
Hello. I'm a new guy in here. Mr. Cnaumann 's solution is so impressive and systematic. Bravo !
I figured out a solution several months ago, although less nimble but...I tried my best :
Weigh (1st time) 4 balls against other 4 (choose randomly).
IF THE SCALE NOT BALANCED: the last 4 balls (not on the scale) are normal ones.
Name the 4 balls on heavier side A,B,C,D. If the odd ball is in group ABCD, it must be heavier than normal one.
Name the 4 balls on lighter side E,F,G,H. If the odd ball is in group EFGH, it must be lighter than normal one.
Weigh (2nd time) : (N is a normal ball)
A B N ~ C D E
1a/ If ABN = CDE : the odd ball is in group F,G,H.
Weigh F against G (3rd time):
If not balanced, the lighter one is the odd ball.
If balanced, H is the odd ball (and is lighter).
1b/ If ABN ≠ CDE :
1b1/ If the scale tipped towards A,B,N side (heavier): the odd ball is in group A,B,E.
Weigh A against B (3rd time) :
If not balanced, the heavier one is the odd ball.
If balanced, E is the odd ball and lighter.
1b2/ If the scale tipped towards C,D,E side : the odd ball is in group C,D.
Weigh C against D. The heavier one is the odd ball.
IF THE SCALE BALANCED (at the 1st weighing) : these 8 balls are normal ones.
Name the last 4 balls A,B,C,D.
Weigh (2nd time) :
A N ~ C D
1a/ If not balanced (AN≠ CD) : the odd ball is in group A,C,D.
1a1/ If the scale tipped towards A,N side :
If the odd ball is A, it must be heavier than normal one. If the odd ball is C or D, it must be lighter than normal one.
Weigh C against D (3rd time):
If not balanced, the lighter one is the odd ball.
If balanced, A is the odd ball and heavier.
1a2/ If the scale tipped towards C,D side :
If the odd ball is A, it must be lighter than normal one. If the odd ball is C or D, it must be heavier than normal one.
Weigh C against D (3rd time) :
If not balanced, the heavier one is the odd ball.
If balanced, A is the odd bal and lighter.
1b/ If balanced (AN=CD) : B is the odd ball.
Weigh B against a normal ball to know if it is lighter or heavier than normal one .