1. Take 1 ball from the first group, 2 balls from the second group, ..., and 10 balls from the 10th group. Weight all those selected balls, and you will know.
-bloor(bloor);
2001-4-18(#48328@0)
Correct! And how about the 2nd question?
-flying_snow(飞雪浮冰);
2001-4-18(#48329@0)
2. 17 min as follows:
-bloor(bloor);
2001-4-18{196}(#48333@0)
Mark the four people as A(1), B(2), C(5), D(10)
1) A(1) & B(2) ----> 2 min
2) A(1) <------ 1 min
3) C(5) & D(10) -----> 10 min
4) B(2) <---- 2 min
5) A(1) & B(2) ----> 2 min
totally 17 min
Great! You are so clever! Admire you! :-)
-flying_snow(飞雪浮冰);
2001-4-18(#48338@0)
Now that you admire me, how about buy me a dinner? ;)
-bloor(bloor);
2001-4-18(#48348@0)
my solution for 1.
-sailor(Sailor);
2001-4-18{233}(#48339@0)
1, Mark the heaps from 1 to 10. pick one ball from heap1, two balls from heap2, 3 balls from heap3, ... and 10 balls from heap10. Weight the balls. Minus the result from 55, the final result is the number of heap of 9-pound balls.