You've got 27 discs, each of them is 10grams, but for 1.
The 1 different disc is 9grams or 11grams (heavier, or lighter by 1g). You
should use balance scale that compares what's in the two pans. You can
get the answer by just comparing groups of discs.
What is the minimum number weighings that can always guarantee to determine the different coin. Please put your answer in the comment box ,If no correct answers by 12pm,I will supply you with the answer .GOODLIUCK
Separate the disk into 3 stacks of 9 (A, B, C). Weigh stack A
ReplyDeleteagainst B and then A against C. Take the stack with the
different weight (note lighter or heavier) and break it into 3
stacks of 3 (D, E, F). Weigh stack D against E. If D and E are
equal, then F is the odd stack. If D and E are not equal, the
lighter or heavier (based on the A, B, C comparison) is the odd
stack. You now have three disk (G, H, I). Weigh G and H. If G
equals H, then I is the odd and is lighter or heavier (based on
the A, B, C comparison). If G and H are not equal, then the
lighter or heavier (based on the A, B, C comparison) is the odd
disk.